In order to ensure long term code quality, add a rubocop check to
the travis job which runs when a pull request is submitted. Do this
by adding a rake task for rubocop and setting up travis to run
both the spec rake task and the rubocop one.
Additionally, make a few changes to the .rubocop.yml file so it
will stop complaining about incorrect namespaces.
Since we want to use rubocop to help maintain the code quality of
this project, add a .rubocop.yml file (borrowed from the puppet repo)
so that we can successfully enforce the things we want and disable
those we don't.