Issue #124: Support Plex GDM protocol for server discovery

Currently we use DLNA but not everybody has it enabled, and there have
been discovery issues using it.  It also brings in Cling which is a fairly
large library and we don't currently support any servers besides plex so
it is unecessary overhead.  Will remove DLNA server discovery in favor
of the leaner GDM implementation.
Set version to 1.3.6 snapshot
Issue #124: Set discovered servers

Once servers are discovered, and a preferred server has not been already
set, choose the first server that was found and connect to it.  Users can
change this in the settings.  Show a toast message saying that it was
auto selected.

If no servers are found, display a message to the user that they need to
set it manually via ip address.