CBQE-1134: cluster status support node down

when a node crashes is failed over or is rebooted this fix
allows us to elect new master.  implementation is simpler
and should support every case where topology changes

Change-Id: Ia91ecad89103c106f690cc0b88cd43ab747c2aa7
Reviewed-on: http://review.couchbase.org/25270
Reviewed-by: Tommie McAfee <tommie@couchbase.com>
Tested-by: Tommie McAfee <tommie@couchbase.com>