.travis.yml in serviceworker-rails-0.3.1 vs .travis.yml in serviceworker-rails-0.4.0

@@ -1,6 +1,5 @@
 language: ruby
 rvm:
-  - 2.1.8
   - 2.2.5
   - 2.3.0
 before_install: gem install bundler -v 1.11.2