.travis.yml in nugrant-2.0.2 vs .travis.yml in nugrant-2.1.0

@@ -2,5 +2,8 @@
 
 rvm:
   - "1.9.3"
   - "2.0.0"
   - "2.1.0"
+
+before_install:
+  - gem install bundler -v '= 1.6.7'