Support hypervisor supplied macs in nova-network
Support hypervisor supplied macs in nova-network

When hypervisors supply a set of MAC addresses for instances, have
nova-network use the supplied values when creating VIFs.

This function is required for the PowerVM driver to be properly
supported.

Change-Id: I922797af6b2b829561f61095bef2098c2d31cde5

n0ano/ganttclient