Clean up chapters controller filters

Some of the before_filters in chapters_controller are missing actions or are filtering different actions for no apparent reasons. This can result in some strange issues:

1. Banned/suspended users can post and delete chapters, but not create or edit.

   1. Abuse says banned and suspended users should not be able to post, create, edit, or delete chapters

2. There's a comment saying admins should be able to delete chapters, but later chapter deletion is restricted to owners only.

   1. Abuse would love for admins to be able to delete chapters, since sometimes they currently end up deleting entire works due to commercial content (e.g. donation links) in one chapter

3. Trying to delete a chapter while logged out results in a redirect to the work rather that to the login page (pending test in for this.

4. The filters indicate that non-work owners can post works, though code below actually prevents this. (pending test in for this).

The filters should be cleaned up so that they make sense and prevent/allow the correct actions.