refs #4386 - add friendly_id dependency

Needed once https://github.com/theforeman/foreman/pull/1246 is merged.

Green scratch builds:
http://koji.katello.org/koji/taskinfo?taskID=162237 f19
http://koji.katello.org/koji/taskinfo?taskID=162238 el6
http://koji.katello.org/koji/taskinfo?taskID=162239 el7