Add ability to schedule backups

[mdylanbell]

Since the actual backup happens via a simple bash script, it's trivial to output the command used to create the backup. It should call some of the php code to create an entry in the backup table, and make sure to remove old backups based on the set number of backups to keep.

A better way would be to create a unified/single cron that can run scheduled backups. I think this is the best way to do it.

[wycks]

This would be really great, how could I use the native media temple cron to run the script though?
http://kb.mediatemple.net/questions/82/Using+Cron#gs