Duplicity will manage the process of creating incremental backups for us.
Although duplicity can both encrypt & copy files to a remote host, I really
don't like PGP and so I don't want to use that.
Instead, we'll back up to a local directory unencrypted, then manually
encrypt the full & incremental backup files. Synchronizing the encrypted
backup directory to a remote host is a TODO.
* Created a new Python/flask-based management daemon.
* Moved the mail user management core code from tools/mail.py to the new daemon.
* tools/mail.py is a wrapper around the daemon and can be run as a non-root user.
* Adding a new initscript for the management daemon.
* Moving dns_update.sh to the management daemon, called via curl'ing the daemon's API.
This also now runs the DNS update after mail users and aliases are added/removed,
which sets up new domains' DNS as needed.
