Class to discover an UPNP device on the network. A multicast
socket will be created to discover devices, the binding port for
this socket is set to 1901, if this is causing a problem you can
use the net.sbbi.upnp.Discovery.bindPort system property to specify
another port.
This class can be used to listen for UPNP devices responses when a
search message is sent by a control point ( using the
net.sbbi.upnp.Discovery.sendSearchMessage() method )