[mythtv] allow DNS names as well as IP addresses in server setup

[Anduin Withers]

> The following patch allows you to put in either hostnames or IP
> addresses in the BackendServerIP and MasterServerIP fields.
> I've only minimally tested it, but it seems to work in my setup.

4. You might want to push it through inet_aton first, only when it is
invalid push it to gethostbyname (instead of defaulting to a lookup and
falling back).

-- 
Anduin Withers