Update .travis.yml

.travis.yml

@@ -2,3 +2,10 @@ language: java
 jdk:
   - oraclejdk8
 script: mvn -fmain/pom.xml clean package
+notifications:
+  webhooks:
+    urls:
+      - https://webhooks.gitter.im/e/7d429ab35361726e26f2
+    on_success: change  # options: [always|never|change] default: always
+    on_failure: always  # options: [always|never|change] default: always
+    on_start: false     # default: false