slightly more generic implementation of getting/setting quota
slightly more generic implementation of getting/setting quota

Change-Id: I1413d73948d355ae5e52b4d7553a9f5c92f768eb
Reviewed-on: http://review.couchbase.org/87655
Tested-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>
Well-Formed: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Aliaksey Artamonau <ce14b1c16e0fd654f926118eb8addbec5aff4ffa@couchbase.com>

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