Feature/kill spam

Fixes #20, LLK/scratchr2#1355 and LLK/scratchr2#1356. Migrations are here because I used them to develop. We may have time to fix South, but the SQL can be generated from these migrations anyway.  I'll talk to @sayamindu tomorrow to figure that out and get this up on jiggler.

Things to note: adds [django-fsm](http://github.com/kmmbvnr/django-fsm) as a requirement, did some slight refactoring to the way the post model does things so that the PostStatus model can manage posts more easily.