Use TravisBuddy to comment on PRs that result in a failed CI build

When the Travis CI build of a pull request fails, TravisBuddy automatically comments. This will cause the pull request author to get a notification and hopefully resolve the issue without the need for any action from one of the repository maintainers.

Author: per1234

.travis.yml

@@ -55,4 +55,10 @@ script:
   - buildExampleSketch ArduinoIoTCloud_LED_switch
   - buildExampleSketch ArduinoIoTCloud_Travis_CI
   - buildExampleUtilitySketch Provisioning
+notifications:
+  webhooks:
+    urls:
+      - https://www.travisbuddy.com/
+    on_success: never
+    on_failure: always