Lea guest can browse posts

Problem: No one could see posts unless they were logged in. 
Fix: Guests can view posts.

Problem: Users could create a post without a category if there were no categories. 
Fix: User must create a category if none exist.

On reddit, anyone signed in can create a subreddit, as long as they're signed in, and it's unique. Uniqueness is a separate feature, not implemented, yet.