Update to work with rails 4 and monologue 0.4.0.beta

I updated to work with rails 4 and monologue 0.4.0, but it was not clear how to test it.  Let me know best way to test it, and I will add tests for the update.  Monologue 0.4.0.beta added the posts_revisions migration to posts, so it had to be removed here.