[rel-3.0.0] point ns_server to rel-3.0.0 branch

Change-Id: Ib6f361b26cbc50a4d97660db2f31d8ed2148c56e
Reviewed-on: http://review.couchbase.org/41059
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>