.travis.yml in serviceworker-rails-0.4.0 vs .travis.yml in serviceworker-rails-0.5.1

@@ -1,5 +1,9 @@
 language: ruby
 rvm:
   - 2.2.5
-  - 2.3.0
-before_install: gem install bundler -v 1.11.2
+  - 2.3.2
+before_install: gem install bundler -v 1.13.6
+gemfile:
+  - gemfiles/rails_3.gemfile
+  - gemfiles/rails_4.gemfile
+  - gemfiles/rails_5.gemfile