Only users to vote
Allow users to switch votes
Destroying a post destroys all its votes
Account deletion destroys user votes
User can access individual comments
Create comment partial, migrate db, update models
Make comments on posts polymorphic

-make comments polymorphic
-make replies controller for comments that reply to other comments
-make new routes for comments and replies
Make replies#create, display comments in nested lists
Refactor replies controller into comments controller
Add permalinks to comments partial
Make comment#create redirect to parent anchor
User can add categories to posts
Add categories to posts
Merge branch 'lea-user-can-make-posts-in-a-category'

* lea-user-can-make-posts-in-a-category:
  Add categories to posts
  User can add categories to posts
  Make comment#create redirect to parent anchor
  Add permalinks to comments partial
  Refactor replies controller into comments controller
  Make replies#create, display comments in nested lists
  Make comments on posts polymorphic
  Create comment partial, migrate db, update models
  User can access individual comments
  Account deletion destroys user votes
  Destroying a post destroys all its votes
  Allow users to switch votes
  Only users to vote