Disconnect from all nodes whenever cookie changes.
Disconnect from all nodes whenever cookie changes.

This is needed because setting new cookie only prevents new
connections from unauthorized nodes. If there's an existing
connection, it won't be closed. This can lead to obscure problems (see
CBSE-2951 for an example).

Change-Id: I782bf5cfef63ff869c52df0caf94024551c1b616
Reviewed-on: http://review.couchbase.org/68980
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Reviewed-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

ceejatec/ns_server,membase/ns_server,ceejatec/ns_server,ceejatec/ns_server,ceejatec/ns_server,membase/ns_server,membase/ns_server,membase/ns_server,membase/ns_server,membase/ns_server,ceejatec/ns_server,ceejatec/ns_server