gnome-mplayer: package also nautilus3 extensions

* fixes QA issues:
gnome-mplayer-1.0.5: gnome-mplayer: Files/directories were installed but not shipped
  /usr/lib
  /usr/lib/nautilus
  /usr/lib/nautilus/extensions-3.0
  /usr/lib/nautilus/extensions-3.0/libgnome-mplayer-properties-page.so
  /usr/lib/nautilus/extensions-3.0/.debug
  /usr/lib/nautilus/extensions-3.0/.debug/libgnome-mplayer-properties-page.so

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>