MySQL support

[ubolonton]

No description provided.

[brendonh]

I think this needs to be a little more robust before it gets merged. Specifically:

• Transaction support is a pretty big deal, or schemup will corrupt DBs in a hard-to-fix way any time an upgrader fails. I'm aware that MySQL doesn't have transactional DDL, but that means we need some other solution.
• The idea with the runLog is that a sysadmin can copy and paste it into the command line to do a supervised upgrade. So it should consist of valid SQL statements
• What's going on with formatMismatch? It would be a nice thing to have, but I see no reason to put it in the DB plugin.