Add environment variable to handle testCoverage

.travis.yml

@@ -1,6 +1,7 @@
 language: android
 jdk: oraclejdk8
 env:
+  - testCoverageEnabled=true
   matrix:
     - ANDROID_TARGET=android-23 ANDROID_ABI=x86
 android:

app/build.gradle

@@ -82,7 +82,7 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
         debug {
-            testCoverageEnabled true
+            testCoverageEnabled System.getenv("testCoverageEnabled") ? System.getenv("testCoverageEnabled").toBoolean() : false
         }
     }
     productFlavors {