rygel: Add recipe

Rygel is a UPnP Audio-Video media server, that allows to
share media files to other devices. It can also become a
MediaRenderer controlled by UPnP or DLNA Controllers.

Rygel makes use of the GStreamer library to recognize and
index media files. UPnp clients will then be able to browse
through them with the aid of metadata (artist, date...).

We do not propose to build without GStreamer support
(because then if cannot parse any actual media file, and
this is pointless), and for the same reason always include
the GStreamer engine in the main package ; but allow
separate packages for plugins.

(disable tracker plugin for now, because it pulls 3 layers
and needs us to have a PREFERRED udev provider, which is a
bit extreme for a first version)

Signed-off-by: Manuel Bachmann <manuel.bachmann@iot.bzh>
Author: Manuel Bachmann <manuel.bachmann@iot.bzh>
Author: Ross Burton <ross.burton@intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>