MB-100 Don't add version to ns_server install directory.

Change-Id: I9b24cf6fe6a89fc9096a59796a54622796980188
Reviewed-on: http://review.couchbase.org/26502
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>