[SSSD] [PATCH] Warn if ad_server contains IP address

[Justin Stephenson]

First patch, see attached.

This is for easy fix from ticket
https://fedorahosted.org/sssd/ticket/2789

I am going on the assumption that if the first 2 characters of ad_server 
are digits then it is likely an IP address and not hostname. If you have 
a better idea for this please let me know.

Kind regards,
Justin Stephenson