re-design ns_server collector (aka ns-to-seriesly)

Change-Id: Ie711c87b875cbc5c2488f405a10d3edcfc8e697d
Reviewed-on: http://review.couchbase.org/24110
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>