notifyd: handle addition of a members key to CMAP

When new key (totem.pg.mrp.srp.members) was added to CMAP,
we would like to receive the trap of this time.

Signed-off-by: Kazunori INOUE <inouekazu@intellilink.co.jp>
Reviewed-by: Jan Friesse <jfriesse@redhat.com>