OpenStack is using nova network, which is deprecated

Hi,

after trying to get the pkb running against a private openstack instance and the HP Helion offering,
I was unable to get the benchmarks started - after some deep digging I found the reason for this:

perfkitbenchmarker/openstack/os_virtual_machine.py is trying to get network information from nova, but in the last few releases, networking has shifted to neutron:

https://blueprints.launchpad.net/nova/+spec/deprecate-nova-network

All public openstack offerings I know off has disabled nova networking, so this should be corrected for pkb

Thanks,
Tom