filesystem: Add media type filtering support
filesystem: Add media type filtering support

Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>

Contains changes by Guillaume Emont <guijemont@igalia.com>

MikePetullo/grilo-plugins,kyoushuu/grilo-plugins,GNOME/grilo-plugins,jasuarez/grilo-plugins,grilofw/grilo-plugins,kyoushuu/grilo-plugins,kyoushuu/grilo-plugins,MikePetullo/grilo-plugins,MikePetullo/grilo-plugins,vrutkovs/grilo-plugins,MathieuDuponchelle/grilo-plugins,MathieuDuponchelle/grilo-plugins,MathieuDuponchelle/grilo-plugins,vrutkovs/grilo-plugins,vrutkovs/grilo-plugins,jasuarez/grilo-plugins,vrutkovs/grilo-plugins,GNOME/grilo-plugins,grilofw/grilo-plugins,MathieuDuponchelle/grilo-plugins