Added data dumps. The can be accessed from the settings menu :)

This ONLY dumps account, posts and comments which YOU have made. This is
not an API.

User IDs (uids) have been replaced with <UID> and password hashes have been
replaced with <PASSWORD HASH>. These are the only thing I can remotely
think would be a security risk, but they probably aren't.

All other data such as votes on posts are not the users property. I would
also not want to dump the zset of uids.

It will be expanded more as and when we add more stuff to the site :D

Comment deleting where a user does not know where the original post is
also needs to be thought about. This could highlight some inaccessible ones.
Post authors can now delete all comments on there posts.

This is a much needed feature as this allows Pjuu to be self moderated.

Unit tests have been added to test this new feature.