MB-11924: added feature to prevent auto-starting of child ports

We're going to use it for memcached to give memcached.json config
manager process to do it's magic prior to actually starting memcached.

Change-Id: Ifdba3d4d430604ad1f7f82c7d07a5027e21dbb9c
Reviewed-on: http://review.couchbase.org/42012
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>