Rework to have member server 'domains' be CN=NETBIOSNAME

Rework to have member server 'domains' be CN=NETBIOSNAME

This reworks quite a few parts of our provision system to use
CN=NETBIOSNAME as the domain for member servers.

This makes it clear that these domains are not in the DNS structure,
while complying with our own schema (found by OpenLDAP's schema
validation).

Andrew Bartlett
(This used to be commit bda6a38b055fed2394e65cdc0b308a1442116402)