Request: MySQL support

[Malkierian]

I'm starting to like PermissionsEx less and less, but I can't seem to find a viable alternative. As far as I can tell, they're the only ones who have SQL support, specifically MySQL, and we NEED that for our server. I think it's the only thing that would keep me from switching over, so if you guys were to add that into this plugin, I would jump to it in a heartbeat.