Domain Controller: Don't require both forwarders
Review Request #245 - Created June 3, 2016 and updated
|mitr, nphilipp, sgallagh, twoerner|
When specifying forwarders for the domain controller, we were checking that both the IPv4 and IPv6 forwarders are present, but we actually only strictly need one or the other (and many environments don't even have both). Change it so that we check for at least one instead. Fixes https://github.com/libre-server/rolekit/issues/64
Tested deployment of a domain controller with only a single IPv4 address.