using never instead of default for webhook

.travis.yml

@@ -81,6 +81,6 @@ notifications:
   webhooks:
     urls:
       - https://webhooks.gitter.im/e/57e15f7798656d888194
-    on_success: change # options: [always|never|change] default: always
-    on_failure: never # options: [always|never|change] default: always
-    on_start: false # default: false
+    on_success: always
+    on_failure: never
+    on_start: never