.travis.yml in rex-bin_tools-0.1.1 vs .travis.yml in rex-bin_tools-0.1.2

@@ -1,5 +1,6 @@
 sudo: false
+group: stable
+cache: bundler
 language: ruby
 rvm:
-  - 2.3.1
-before_install: gem install bundler -v 1.12.5
+  - 2.3.3