Removed unused metadata key and do_rmdir func

Change-Id: Ibcef5d817390a11d85cf125bb9addfbfded1b019
Signed-off-by: Luis Pabon <lpabon@redhat.com>
Reviewed-on: http://review.gluster.org/5301
Reviewed-by: Mohammed Junaid <junaid@redhat.com>
Reviewed-by: Peter Portante <pportant@redhat.com>
Tested-by: Peter Portante <pportant@redhat.com>