Strict minimum bandwidth support (scheduling aware)

Newton release added minimum bandwidth support to QoS policy
rules. While this improvement works at the hypervisor level,
it's a best effort measure that will not prevent oversusbcription
on a specific network link bandwidth (When SUM i port[i].min_bw >
max available bandwidth within a provider network).

NFV/Telcos are interested in this type of rules to make sure
functions don't over commit compute nodes.

CSPs could make use of this feature to provide bandwidth
guarantees for streaming.