.travis.yml in rack-simple_user_agent-0.2.1 vs .travis.yml in rack-simple_user_agent-0.2.2

@@ -1,5 +1,6 @@
 language: ruby
+cache: bundler
 rvm:
-  - 2.2
-  - 2.3.0
+  - 2.2.4
+  - 2.3.1
 before_install: gem install bundler -v 1.11.2