MB-10400 re-factor: extract upr commands into separate module

Change-Id: I30901a693e7216db5b1091a953037de785dd8f7c
Reviewed-on: http://review.couchbase.org/34268
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>