Sometimes, libvirt tells us too late that a domain has been removed.

Handles correctly termination.

Clean authentication code.

This is a fix when is the same poll we try to update a tag value for a VM and
the domain just has been removed.

Needed for disk synchronisation during live migration.

Type is the same as returned by libvirt (for now).
One of dir, fs, netfs, logical, disk, iscsi, mpath, rbd.

Harmless renaming.