added upr_commands:setup_flow_control/2

Change-Id: I0eb392942a6f92e743e1c4f4ba45b22ac9c3372e
Reviewed-on: http://review.couchbase.org/37343
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>