mongoid/mongoid — pull request #3333 by arthurnn (2013-10-20 00:52:57+00:00)
Title: Don`t run only after_callbacks

Can see here 2b043206ee99e9217dc5bd3ff3b6ede09430574a that some run_callbacks were removed,
However there was some run_after_callbacks left, which make no sense to be ran.

@durran want your opinion on this. IMO it make sense to only run callbacks when both, before and after, are executed. I think that was left over code, also that I didnt have to change any test to remove them.
Also I am removing `post_persist`, which should not belong to the dirty attributes module.