Log Message:
Update ruby-bundler to 1.14.6.

Changes are too many to write here, please refer these release announce.

http://bundler.io/blog/2015/12/12/version-1-11-released.html
http://bundler.io/blog/2016/04/28/the-new-index-format-fastly-and-bundler-1-12.html
http://bundler.io/blog/2016/09/08/bundler-1-13.html
http://bundler.io/blog/2017/03/28/bundler-1-14-so-many-fixes.html