removing unnecessary hook in travis file

Author: Simonas Šerlinskas

Diff for: .travis.yml

@@ -16,9 +16,3 @@ script:
   - vendor/bin/phpcs -p --standard=PSR2 --ignore=vendor/ ./
 after_script:
   - vendor/bin/coveralls
-notifications:
-  webhooks:
-    urls:
-      - https://webhooks.gitter.im/e/81e47479feba5ba8dc47
-    on_success: change
-    on_start: never