Add gitter webhook to travis config (#296)

.travis.yml

@@ -33,6 +33,12 @@ matrix:
 # Don't email me the results of the test runs.
 notifications:
   email: false
+  webhooks:
+    urls:
+      - https://webhooks.gitter.im/e/ec30ac1bb280c976f8be
+    on_success: change  # options: [always|never|change] default: always
+    on_failure: always  # options: [always|never|change] default: always
+    on_start: never     # options: [always|never|change] default: always
 
 # Anything in before_script that returns a nonzero exit code will
 # flunk the build and immediately stop. It's sorta like having