Store config_version of other nodes

Config version of other nodes is stored in
runtime.totem.pg.mrp.srp.members.NODEID.config_version key. Also when
local config_version is changed, all nodes are informed.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Fabio M. Di Nitto <fdinitto@redhat.com>