refresh bucket info cache on node's membership changes

So that we refresh bucket info cache on niql node failover.

Change-Id: I862f2ff95eac7c481f9662f020a85e7fd9919537
Reviewed-on: http://review.couchbase.org/43152
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>