Creating a user select for backup folders

[joebordes]

This is something I would accept, I think it is useful as many installs have the same problem and most end up disabling the internal backups and using an external backup system.

We now have two backup systems in coreBOS so you will have to adapt both:

https://github.com/tsolucio/corebos/blob/master/modules/VtigerBackup/VtigerBackup.php#L29
https://github.com/tsolucio/corebos/blob/master/cron/modules/VtigerBackup/ExternalBackup.service#L58

and then modify ExternalBackup.service and the backup() method to call a "cleanup old backups" method