Add OSX build on travis (#1502)

Also make test script works for OSX script command.
diff --git a/.travis.yml b/.travis.yml
index 70b1fd0..19a9b28 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,12 @@
+matrix:
+  include:
+    - os: linux
+      compiler: gcc
+    - os: linux
+      compiler: clang
+    - os: osx
 sudo: false
 language: cpp
-compiler:
-  - gcc
-  - clang
 script:
   - ./configure.py --bootstrap
   - ./ninja all
diff --git a/misc/output_test.py b/misc/output_test.py
index 878de19..1dcde10 100755
--- a/misc/output_test.py
+++ b/misc/output_test.py
@@ -6,6 +6,7 @@
 """
 
 import os
+import platform
 import subprocess
 import sys
 import tempfile
@@ -26,6 +27,9 @@
         try:
             if pipe:
                 output = subprocess.check_output([ninja_cmd], shell=True, env=env)
+            elif platform.system() == 'Darwin':
+                output = subprocess.check_output(['script', '-q', '/dev/null', 'bash', '-c', ninja_cmd],
+                                                 env=env)
             else:
                 output = subprocess.check_output(['script', '-qfec', ninja_cmd, '/dev/null'],
                                                  env=env)
@@ -43,7 +47,7 @@
     def test_issue_1418(self):
         self.assertEqual(run(
 '''rule echo
-  command = sleep 0.$delay && echo $out
+  command = sleep $delay && echo $out
   description = echo $out
 
 build a: echo