.travis.yml in oxr-0.2.0 vs .travis.yml in oxr-0.4.0

@@ -1,6 +1,7 @@
 language: ruby
 rvm:
-  - 2.1.8
-  - 2.2.4
-  - 2.3.0
-before_install: gem install bundler -v 1.11.2
+  - 2.1.10
+  - 2.2.6
+  - 2.3.3
+  - 2.4.1
+before_install: gem install bundler -v 1.14.6