Replace some android.support references with androidx (#468)

* replace android.support references with androidx

* clarify in documentation that package for android.support is in flux

* make it a todo

partially addresses #470 
diff --git a/mobly/base_instrumentation_test.py b/mobly/base_instrumentation_test.py
index 218be6a..1a28de7 100644
--- a/mobly/base_instrumentation_test.py
+++ b/mobly/base_instrumentation_test.py
@@ -85,6 +85,8 @@
         android.app.Instrumentation
         android.support.test.internal.runner.listener.InstrumentationResultPrinter
 
+    TODO: Convert android.support.* to androidx.*,
+    (https://android-developers.googleblog.com/2018/05/hello-world-androidx.html).
     """
 
     CLASS = 'class'
@@ -119,6 +121,8 @@
 
         android.support.test.internal.runner.listener.InstrumentationResultPrinter
 
+    TODO: Convert android.support.* to androidx.*,
+    (https://android-developers.googleblog.com/2018/05/hello-world-androidx.html).
     """
 
     UNKNOWN = None
diff --git a/tests/mobly/base_instrumentation_test_test.py b/tests/mobly/base_instrumentation_test_test.py
index 64cd09c..8dc5e5f 100755
--- a/tests/mobly/base_instrumentation_test_test.py
+++ b/tests/mobly/base_instrumentation_test_test.py
@@ -418,9 +418,9 @@
 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:59)
 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
-	at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
-	at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
-	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
+	at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
+	at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
+	at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
 	at com.my.package.test.BaseTest$3.evaluate(BaseTest.java:96)
 	at com.my.package.test.BaseTest$4.evaluate(BaseTest.java:109)
 	at com.my.package.test.BaseTest$2.evaluate(BaseTest.java:77)
@@ -437,7 +437,7 @@
 	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:60)
 	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:270)
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
-	at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
+	at androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
 	at org.junit.runners.Suite.runChild(Suite.java:128)
 	at org.junit.runners.Suite.runChild(Suite.java:27)
 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:292)
@@ -456,7 +456,7 @@
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
-	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
+	at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
 	at com.my.package.test.BaseRunner.runTests(BaseRunner.java:344)
 	at com.my.package.test.BaseRunner.onStart(BaseRunner.java:330)
 	at com.my.package.test.runner.MyRunner.onStart(MyRunner.java:253)
@@ -471,9 +471,9 @@
 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:59)
 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
-	at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
-	at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
-	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
+	at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
+	at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
+	at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
 	at com.my.package.test.BaseTest$3.evaluate(BaseTest.java:96)
 	at com.my.package.test.BaseTest$4.evaluate(BaseTest.java:109)
 	at com.my.package.test.BaseTest$2.evaluate(BaseTest.java:77)
@@ -490,7 +490,7 @@
 	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:60)
 	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:270)
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
-	at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
+	at androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
 	at org.junit.runners.Suite.runChild(Suite.java:128)
 	at org.junit.runners.Suite.runChild(Suite.java:27)
 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:292)
@@ -509,7 +509,7 @@
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
-	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
+	at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
 	at com.my.package.test.BaseRunner.runTests(BaseRunner.java:344)
 	at com.my.package.test.BaseRunner.onStart(BaseRunner.java:330)
 	at com.my.package.test.runner.MyRunner.onStart(MyRunner.java:253)
@@ -529,9 +529,9 @@
 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:59)
 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
-	at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
-	at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
-	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
+	at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
+	at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
+	at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
 	at com.my.package.test.BaseTest$3.evaluate(BaseTest.java:96)
 	at com.my.package.test.BaseTest$4.evaluate(BaseTest.java:109)
 	at com.my.package.test.BaseTest$2.evaluate(BaseTest.java:77)
@@ -548,7 +548,7 @@
 	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:60)
 	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:270)
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
-	at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
+	at androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
 	at org.junit.runners.Suite.runChild(Suite.java:128)
 	at org.junit.runners.Suite.runChild(Suite.java:27)
 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:292)
@@ -567,7 +567,7 @@
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
-	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
+	at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
 	at com.my.package.test.BaseRunner.runTests(BaseRunner.java:344)
 	at com.my.package.test.BaseRunner.onStart(BaseRunner.java:330)
 	at com.my.package.test.runner.MyRunner.onStart(MyRunner.java:253)
@@ -607,9 +607,9 @@
 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:59)
 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
-	at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
-	at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
-	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
+	at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
+	at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
+	at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
 	at com.my.package.test.MyBaseTest$3.evaluate(MyBaseTest.java:96)
 	at com.my.package.test.MyBaseTest$4.evaluate(MyBaseTest.java:109)
 	at com.my.package.test.MyBaseTest$2.evaluate(MyBaseTest.java:77)
@@ -626,7 +626,7 @@
 	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:60)
 	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:270)
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
-	at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
+	at androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
 	at org.junit.runners.Suite.runChild(Suite.java:128)
 	at org.junit.runners.Suite.runChild(Suite.java:27)
 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:292)
@@ -645,7 +645,7 @@
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
-	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
+	at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
 	at com.my.package.test.runner.BaseRunner.runTests(BaseRunner.java:344)
 	at com.my.package.test.runner.BaseRunner.onStart(BaseRunner.java:330)
 	at com.my.package.test.runner.BaseRunner.onStart(BaseRunner.java:253)
@@ -827,9 +827,9 @@
 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:59)
 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
-	at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
-	at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
-	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
+	at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
+	at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
+	at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
 	at com.my.package.test.BaseTest$3.evaluate(BaseTest.java:96)
 	at com.my.package.test.BaseTest$4.evaluate(BaseTest.java:109)
 	at com.my.package.test.BaseTest$2.evaluate(BaseTest.java:77)
@@ -846,7 +846,7 @@
 	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:60)
 	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:270)
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
-	at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
+	at androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
 	at org.junit.runners.Suite.runChild(Suite.java:128)
 	at org.junit.runners.Suite.runChild(Suite.java:27)
 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:292)
@@ -865,7 +865,7 @@
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
-	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
+	at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
 	at com.my.package.test.BaseRunner.runTests(BaseRunner.java:344)
 	at com.my.package.test.BaseRunner.onStart(BaseRunner.java:330)
 	at com.my.package.test.runner.MyRunner.onStart(MyRunner.java:253)
@@ -880,9 +880,9 @@
 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:59)
 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
-	at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
-	at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
-	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
+	at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
+	at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
+	at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
 	at com.my.package.test.BaseTest$3.evaluate(BaseTest.java:96)
 	at com.my.package.test.BaseTest$4.evaluate(BaseTest.java:109)
 	at com.my.package.test.BaseTest$2.evaluate(BaseTest.java:77)
@@ -899,7 +899,7 @@
 	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:60)
 	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:270)
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
-	at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
+	at androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
 	at org.junit.runners.Suite.runChild(Suite.java:128)
 	at org.junit.runners.Suite.runChild(Suite.java:27)
 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:292)
@@ -918,7 +918,7 @@
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
-	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
+	at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
 	at com.my.package.test.BaseRunner.runTests(BaseRunner.java:344)
 	at com.my.package.test.BaseRunner.onStart(BaseRunner.java:330)
 	at com.my.package.test.runner.MyRunner.onStart(MyRunner.java:253)
@@ -945,9 +945,9 @@
 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:59)
 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
-	at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
-	at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
-	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
+	at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
+	at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
+	at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
 	at com.my.package.test.BaseTest$3.evaluate(BaseTest.java:96)
 	at com.my.package.test.BaseTest$4.evaluate(BaseTest.java:109)
 	at com.my.package.test.BaseTest$2.evaluate(BaseTest.java:77)
@@ -964,7 +964,7 @@
 	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:60)
 	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:270)
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
-	at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
+	at androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
 	at org.junit.runners.Suite.runChild(Suite.java:128)
 	at org.junit.runners.Suite.runChild(Suite.java:27)
 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:292)
@@ -983,7 +983,7 @@
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
-	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
+	at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
 	at com.my.package.test.BaseRunner.runTests(BaseRunner.java:344)
 	at com.my.package.test.BaseRunner.onStart(BaseRunner.java:330)
 	at com.my.package.test.runner.MyRunner.onStart(MyRunner.java:253)
@@ -1032,9 +1032,9 @@
 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:59)
 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
-	at android.support.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
-	at android.support.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
-	at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
+	at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
+	at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
+	at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:433)
 	at com.my.package.test.BaseTest$3.evaluate(BaseTest.java:96)
 	at com.my.package.test.BaseTest$4.evaluate(BaseTest.java:109)
 	at com.my.package.test.BaseTest$2.evaluate(BaseTest.java:77)
@@ -1051,7 +1051,7 @@
 	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:60)
 	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:270)
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
-	at android.support.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
+	at androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:99)
 	at org.junit.runners.Suite.runChild(Suite.java:128)
 	at org.junit.runners.Suite.runChild(Suite.java:27)
 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:292)
@@ -1070,7 +1070,7 @@
 	at org.junit.runners.ParentRunner.run(ParentRunner.java:370)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 	at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
-	at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
+	at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
 	at com.my.package.test.BaseRunner.runTests(BaseRunner.java:344)
 	at com.my.package.test.BaseRunner.onStart(BaseRunner.java:330)
 	at com.my.package.test.runner.MyRunner.onStart(MyRunner.java:253)