Avoid updating rubygems, it might break for older rubies

Author: andrehjr

.travis.yml

@@ -44,7 +44,7 @@ matrix:
 
 
 before_install:
-  - gem update --system && gem install bundler
+  - gem install bundler --version=1.17.3
 
 script:
   - RAILS_ENV=test bundle exec rake spec && bundle exec codeclimate-test-reporter