Add stream end implementation for upr producer

For now if we have a stream just send a stream end message and
close that stream.

Change-Id: I301f08b408b8ecd66fd160785543811a3022a10c
Reviewed-on: http://review.couchbase.org/30026
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>