make upr be default replication type

As per request earlier agreement.

Change-Id: I40fad997cfb05f7dd486f0bc6956e516b8eb1215
Reviewed-on: http://review.couchbase.org/37511
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>