improved slow bucket stop diagnostic
improved slow bucket stop diagnostic

Change-Id: I00c816b20e316ae5bad57ecd7fae3aa4e8a7d39d
Reviewed-on: http://review.couchbase.org/52272
Tested-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>

ceejatec/ns_server,mschoch/ns_server,mschoch/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,membase/ns_server,mschoch/ns_server,nimishzynga/ns_server,mschoch/ns_server,ceejatec/ns_server,mschoch/ns_server,ceejatec/ns_server,nimishzynga/ns_server,mschoch/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,membase/ns_server,nimishzynga/ns_server,ceejatec/ns_server,nimishzynga/ns_server