Fixes #414 - integrates rubocop gem

Adds rubocop gem and fixes majority of issues noted by cop.
By moving it to a new line, it's not clear that this line is still part of the URL. I would just get rid of all of those comments. By placing a gem inside a group, you are implicitly letting the developer know that the gem belongs in that group only. Comments that state that the gem should only be run in production are redundant.