Real time backup of storage engine databases

Per request from Adrian and Rackspace, we need to add the ability within Drizzle to do real time backups of the databases for the currently running database. We can start with innodb and then see about getting this to work with the other supported storage engines. This ties in with providing multi-tenancy support for Drizzle as once we have many users on the same database we must be able to back it up without affecting the different users