Comment restrictions

Added functionality for users to comment restrictions. This is a very wanted functionality in kansalaisaloite.fi which we apparently are not going to implement because the purpose of the service is not to chat with people but to gather statements of supports. So I decided to implement it here.

This commenting functionality requires the user to be logged in. Added necessary sql-increment, styles and other stuff. I've never actually before used python, mustache etc so feel free to make changes, but everything seemed to work just well on my local environment.