.travis.yml in yao-0.3.7 vs .travis.yml in yao-0.3.8

@@ -10,11 +10,16 @@
 
 cache:
   directories: vendor/bundle
 
 script:
+  - bundle exec rubocop
   - bundle exec rake test
   - find lib -name '*.rb' | xargs -i ruby -wc {}
 
 notifications:
   slack:
     secure: 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
+
+matrix:
+  allow_failures:
+    - rvm: ruby-head