Refactor: rename UPR to DCP

Change-Id: Idc9f5c4561fbf5bf011ca1dbed5ad00a64c67fa0
Reviewed-on: http://review.couchbase.org/39747
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>