.travis.yml in gibbon-3.1.0 vs .travis.yml in gibbon-3.1.1

@@ -1,7 +1,9 @@
 language: ruby
 sudo: false
 cache: bundler
+before_install:
+  - gem install bundler # -v 1.7.14 if a specific version is needed
 rvm:
   - 2.0.0
   - 2.1.5
   - 2.2.2
   - 2.3.3
\ No newline at end of file