Add uPnP support

[clementleger]

It should be nice to add uPnP support.
The idea would be to use a separate binary to link with an external lib.
There is 2 use cases:

• Control devices which implement MediaRenderer & AVTransport like other AVReceiver
• Get Media informations from server and stream them to a uPnP device

Various Libraries are available:

• pupnp (C, difficult to use according to users)
• Platinum UPNP (Come with a custom C++ runtime...)
• Gupnp (uses Glib...)