Added UPR prototype

Change-Id: I947f2a82eab6861a12c4a8d25b3783b0e6bd8b10
Reviewed-on: http://review.couchbase.org/28859
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>