Add Slack build notifications.

.travis.yml

@@ -1,23 +1,16 @@
 language: ruby
-
 cache: bundler
-
 sudo: false
-
 rvm:
-  - 2.1
-  - 2.0
-  - 1.9.3
-
+- 2.1
+- 2.0
+- 1.9.3
 env:
   matrix:
-    - TEST_SUITE=test
-    - TEST_SUITE=cucumber
-
+  - TEST_SUITE=test
+  - TEST_SUITE=cucumber
 before_script: bundle update
-
 script: script/cibuild
-
 notifications:
   irc:
     on_success: change
@@ -25,7 +18,9 @@ notifications:
     channels:
     - irc.freenode.org#jekyll
     template:
-    - '%{repository}#%{build_number} (%{branch}) %{message} %{build_url}'
+    - "%{repository}#%{build_number} (%{branch}) %{message} %{build_url}"
   email:
     on_success: never
     on_failure: never
+  slack:
+    secure: dNdKk6nahNURIUbO3ULhA09/vTEQjK0fNbgjVjeYPEvROHgQBP1cIP3AJy8aWs8rl5Yyow4YGEilNRzKPz18AsFptVXofpwyqcBxaCfmHP809NX5PHBaadydveLm+TNVao2XeLXSWu+HUNAYO1AanCUbJSEyJTju347xCBGzESU=