MB-9338: added ns_ssl_proxy

Based on initial implementation by Artem Stemkovski.

Change-Id: Ic5f89cd89f3463a84698eb4b6cfd19d89415e4f1
Reviewed-on: http://review.couchbase.org/31373
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>