Skip sample app builds on travis

Author: ajungg

.travis.yml

@@ -11,7 +11,7 @@ android:
 before_install:
     - yes | sdkmanager "platforms;android-27"
 script:
-- "./gradlew build"
+- "./gradlew :core:assembleRelease :ui:assembleRelease :ui-integration:assembleRelease :utils:assembleRelease"
 cache:
   directories:
   - "$HOME/.gradle/caches/"