switch branch-2.0.2 to use 2.0.2 branch of ns_server

Change-Id: Ic800a8661a89c14e271b3008b02158e5433e12ec
Reviewed-on: http://review.couchbase.org/26279
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>