core: Don't spam the user's config dir
core: Don't spam the user's config dir

Put the description files into a subdir under user's config dir.

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