Don't collapse checkpoints when registering an upr cursor

Change-Id: Ic0d64518454a7357871362d7045926ddb708e3b4
Reviewed-on: http://review.couchbase.org/39556
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>