[rel-3.0.0] update ns_server for MB-12030, MB-11995 and MB-11996

It also adds approved addition of LICENSE file to erlwsh component.

Change-Id: I39a2a3509f41b5a99bdcce8d95d77f1803c2440d
Reviewed-on: http://review.couchbase.org/40758
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>