Remove UprLogElement class

This class is no longer needed for the flow control method that
upr will be using.

Change-Id: Ic1c84e609744052a8b09490e2466ff4f7b0ee8eb
Reviewed-on: http://review.couchbase.org/34372
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>
Remove expiry window stat

We no longer support the expiry window since we now require that
all documents are persisted.

Change-Id: Id3e9aadced5187f6b1b5d817a3497c9997485740
Reviewed-on: http://review.couchbase.org/34373
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>
Fix valgrind errors

Change-Id: I353cf0137bcb97a51afaf4fba23d172a067e25ef
Reviewed-on: http://review.couchbase.org/34374
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>