[SSSD] [PATCH] DYNDNS: Add a new option dyndns_server

[Jakub Hrozek]

Hi,

one of our users ran into an interesting problem -- her AD
infrastructure was different from the DNS server. Because by default, we
perform update against the server we're connected to, the DNS update
didn't work.

Per Simo's suggestion, I've implemented a new option that allows the
administrator to override the DNS server used for DNS updates.