allow overriding certain service_status_keeper parameters per service
allow overriding certain service_status_keeper parameters per service

...also keep the support of legacy pre vulcan keys

Change-Id: I07d38766d0b0784e8ff3800d9cd5332a3dc3372f
Reviewed-on: http://review.couchbase.org/88542
Reviewed-by: Aliaksey Artamonau <ce14b1c16e0fd654f926118eb8addbec5aff4ffa@couchbase.com>
Tested-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

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