Stay on Bundler 1.17.3 for TravisCI

Author: drwl

.travis.yml

@@ -10,10 +10,6 @@ matrix:
   allow_failures:
   - rvm: ruby-head
 
-before_install:
-- yes | gem update --system
-- gem update bundler
-
 script:
 - bundle exec rubocop && bundle exec rspec