MB-9898: Add byte sizes to upr responses

The sizes in this change represent the amount of bytes that each
upr message requires when being sent over a network connection.

Change-Id: Ic90bffc6ced9a7f9b4c6624289e0eb42e0caaaf6
Reviewed-on: http://review.couchbase.org/35374
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>