Added pagination

Added a couple of gems and pagination to the thread index and to the post list in thread.
Threads now make their own dummy posts

No longer do we need forum_thread.as_post, the thread body is just the first post in a thread now.
Added edit and delete icons to posts.
Added a moderation UI.

Moderation UI doesn't do anything, but it lists all the posts and threads that have been complained about, as well as the people who complained about them. Only visible to VIPs.