Add gitter notifications

Author: larryxiao625

.travis.yml

@@ -33,3 +33,10 @@ deploy:
     tags: true
 after_deploy:
 - fir p app/build/outputs/apk/app-release.apk -T $FIR_TOKEN -c "`git cat-file tag $TRAVIS_TAG`"
+notifications:
+  webhooks:
+    urls:
+      - https://webhooks.gitter.im/e/d83cc8365de0abdd097e
+    on_success: always  # options: [always|never|change] default: always
+    on_failure: always  # options: [always|never|change] default: always
+    on_start: always     # options: [always|never|change] default: always