Before this change, for --exclude-data to work one must specify
--exclude-system too. This is no longer the case and both options
now work independently.

We made an assumption that the filesystem has not been snapshotted,
in the case that it could be snapshotted we certainly do not want
to exclude mysql & pgsql from the backups.

Treat /tmp and /var/tmp as data directories

This will help in future when we need to do cleanups

If we exit when tar fails we may not get to backup whats after it.

Thanks to Psi-Jack for picking it up

Document version upgrades

Document version upgrades

Added --backup-upgrade option to upgrade data

Fixed up messages displayed a bit

Fixed bug reporting tar exit status
Use lchown not chown when chowing on restore
Don't chmod & utime for symlinks
Fixed UNKNOWN displaying in the logs insted of ERROR