[aetest] Fix Federated-Identity headers (#224)

* Fix Federated-Identity headers
* Use user.FederatedIdentity instead of user.Email
* Fix out-of-range test
* Remove go1.8 tests
diff --git a/.travis.yml b/.travis.yml
index 70ffe89..6d03f4d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,8 +10,6 @@
 
 matrix:
   include:
-    - go: 1.8.x
-      env: GOAPP=true
     - go: 1.9.x
       env: GOAPP=true
     - go: 1.10.x
diff --git a/aetest/user.go b/aetest/user.go
index bf9266f..52b4a16 100644
--- a/aetest/user.go
+++ b/aetest/user.go
@@ -16,6 +16,9 @@
 		id = strconv.Itoa(int(crc32.Checksum([]byte(u.Email), crc32.IEEETable)))
 	}
 	req.Header.Set("X-AppEngine-User-Id", id)
+	req.Header.Set("X-AppEngine-Federated-Identity", u.FederatedIdentity)
+	req.Header.Set("X-AppEngine-Federated-Provider", u.FederatedProvider)
+	// NOTE: the following two headers are wrong, but are preserved to not break legacy tests.
 	req.Header.Set("X-AppEngine-User-Federated-Identity", u.Email)
 	req.Header.Set("X-AppEngine-User-Federated-Provider", u.FederatedProvider)
 	if u.Admin {
@@ -31,6 +34,9 @@
 	req.Header.Del("X-AppEngine-User-Email")
 	req.Header.Del("X-AppEngine-User-Id")
 	req.Header.Del("X-AppEngine-User-Is-Admin")
+	req.Header.Del("X-AppEngine-Federated-Identity")
+	req.Header.Del("X-AppEngine-Federated-Provider")
+	// NOTE: the following two headers are wrong, but are preserved to not break legacy tests.
 	req.Header.Del("X-AppEngine-User-Federated-Identity")
 	req.Header.Del("X-AppEngine-User-Federated-Provider")
 }
diff --git a/internal/api_test.go b/internal/api_test.go
index 8369b33..aa36029 100644
--- a/internal/api_test.go
+++ b/internal/api_test.go
@@ -415,7 +415,7 @@
 	}
 
 	// Lots of room for improvement...
-	const min, max float64 = 60, 85
+	const min, max float64 = 60, 86
 	if avg < min || max < avg {
 		t.Errorf("Allocations per API call = %g, want in [%g,%g]", avg, min, max)
 	}