chore: travis-slack integration

Author: mhevery

.travis.yml

@@ -30,7 +30,9 @@ after_script:
 notifications:
   webhooks:
     urls:
-      - https://webhooks.gitter.im/e/1ef62e23078036f9cee4
+    - https://webhooks.gitter.im/e/1ef62e23078036f9cee4
     on_success: change  # options: [always|never|change] default: always
     on_failure: always  # options: [always|never|change] default: always
     on_start: false     # default: false
+  slack:
+    secure: EP4MzZ8JMyNQJ4S3cd5LEPWSMjC7ZRdzt3veelDiOeorJ6GwZfCDHncR+4BahDzQAuqyE/yNpZqaLbwRWloDi15qIUsm09vgl/1IyNky1Sqc6lEknhzIXpWSalo4/T9ZP8w870EoDvM/UO+LCV99R3wS8Nm9o99eLoWVb2HIUu0=