MB-4345 Add function that restarts memcached port.

Change-Id: I11dc7c37536fad3db086e820f6decbd7ac7dc079
Reviewed-on: http://review.couchbase.org/29070
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>