Updated to integrate with vagrant cleaner

* Configured vagrant provision to execute as a role so defaults are properly
  loaded.
* Moved test vars to Vagrantfile explicit loading
* No longer need to ignore `vagrant_ansible_inventory_default` with a newer
  version of Vagrant.
* Updated Vagrant file to conform to Rubocop syntax.
Correctly escaped the pluralization
Merge pull request #9 from retr0h/retr0h/cleanup-vagrant

Updated to integrate with vagrant cleaner