DYNDNS: Add a new option dyndns_server
Some environments use a different DNS server than identity server. For
these environments, it would be useful to be able to override the DNS
server used to perform DNS updates.
This patch adds a new option dyndns_server that, if set, would be used
to hardcode a DNS server address into the nsupdate message.
Reviewed-by: Pavel Reichl <preichl@redhat.com>