Add rubygem-bastion package

Alright, the final one in line. Scratches:

F19 http://koji.katello.org/koji/taskinfo?taskID=171319
EL6 http://koji.katello.org/koji/taskinfo?taskID=171320
EL7 http://koji.katello.org/koji/taskinfo?taskID=171321
I assume you mean in the plugin definition? I don't think I added a plugin declaration formally to the code since it doesn't provide any direct functionality itself at the moment. If you prefer I add it and fix this up with a new version of the gem I can.