Silence `:rubygems` Bundler deprecation notice.
Silence `:rubygems` Bundler deprecation notice.

Message from Bundler before this change:

The source :rubygems is deprecated because HTTP requests are insecure.

Please change your source to 'https://rubygems.org' if possible, or
'http://rubygems.org' if not.

AJ56321/hubot,jdhebden/hubot,jdhebden/hubot,AJ56321/hubot,jdhebden/hubot,tas50/hubot,AJ56321/hubot