[Katello] Removing Old Auth System


Today a commit is going in to master that effectively removes the entirety
of the old Katello authorization system. This commit may requires
developers to do a full reset rake katello:reset (and in some instances,
if you notice a failing migration, running it a second time) if witnessing
strange behaviors. Similar to other changes we've made on our way to 2.0,
this effectively removes the old auth system as if it never existed

Relevant PR - https://github.com/Katello/katello/pull/4329