Specify correct build tools and build script

Author: dsavenko

.travis.yml

@@ -2,7 +2,7 @@ language: android
 
 android:
     components:
-        - build-tools-19.1.0
+        - build-tools-23.0.2
         - android-22
 
 before_cache:
@@ -12,3 +12,5 @@ cache:
     directories:
         - $HOME/.gradle/caches/
         - $HOME/.gradle/wrapper/
+
+script: ./gradlew assembleRelease