Add vbucket uuid to stats vbucket-seqno

Change-Id: I12934f04d8ceb264ce8e11541b7db9f57dc737f8
Reviewed-on: http://review.couchbase.org/32393
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>