MB-1143: disallow rackawareness APIs for non-enterprise edition

Change-Id: I8f6d6938885b20b55f509347197ea31ebbec1454
Reviewed-on: http://review.couchbase.org/30153
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Artem Stemkovski <artem@couchbase.com>