fix travis

Author: onyxraven

.travis.yml

@@ -6,5 +6,7 @@ rvm:
   - "2.2.4"
   - "2.3.1"
   - "jruby-9.0.5.0"
+before_install:
+  - gem install bundler
 # uncomment this line if your project needs to run something other than `rake`:
 # script: bundle exec rspec spec