Add Slack notifications for Travis build

This is a differentiator and will never be merged upstream
(cherry picked from commit 5e733d0)

Author: ArturGajowy

.travis.yml

@@ -61,7 +61,10 @@ before_cache:
 
 notifications:
   slack:
-    secure: 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
+    rooms:
+      - secure: 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
+    on_success: change
+    on_failure: always
 
 before_deploy:
   - mkdir /tmp/artifacts