Add a status field to the add stream response

We need to be able to communicate errors when calling this api

Change-Id: Iebcd39ed8200b9543d2c994f08eb6be421a87cb1
Reviewed-on: http://review.couchbase.org/30267
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>