For the F19 live DVD we have cheese -> gnome-video-effects
->frei0r-plugins -> opencv, the last being 31M on disk (20 of which,
appallingly, is XML). opencv is only used for the face-detection
plugins in frei0r. The only other consumer of frei0r-plugins in the OS
is pitivi, and neither it nor g-v-e uses the face-detection plugins.
Move them to a subpackage to break the dep chain.
Signed-off-by: Adam Jackson <ajax@redhat.com>