Provide a const for generic UPnP audio item class.
Provide a const for generic UPnP audio item class.

svn path=/trunk/; revision=333

jku/rygel,Pelagicore/Media-Manager-Rygel-patched,Pelagicore/Media-Manager-Rygel-patched,Tarnyko/rygel,GNOME/rygel,jku/rygel,luisbg/rygel,Pelagicore/Media-Manager-Rygel-patched,GNOME/rygel,GNOME/rygel,Tarnyko/rygel