Support switch QOS

[henn]

Currently, HaaS supports isolation in terms of addressability. To fully support isolation, performance would also need to be considered.

For example, if production workloads are sharing a single switch with network-intensive experimental workloads, the potential exists that uplinks outside of that switch could become saturated.

To address this, some form of QOS should be supported. Since isolation is one of the fundamental features of HaaS, there is a strong case for including support within the API in a vendor-neutral way.

One caveat is that computing the set of policies that will enable a certain QOS request may become a complicated matter, especially if the network configuration is complex. The ideal solution is probably NP hard, though a good research topic would be to see if this is necessarily the case or what approximations exist.