RFR: Neutron driver

This is a pretty naive stab at adding a networking provider framework and an openstack neutron driver.

These changes will only create/delete logical ports on instance create/delete. 

This can (in theory) be extended pretty easily to allow for user-defined private networks. It might also be worth implementing a simple dhcp-only provider.

In order for this to work in real life:

1. We'll have to set up and configure neutron somewhere with the right plugin that can configure our hardware (which I'll have to look into).
2. Because we won't have a host agent we'll have to pull some of the configuration data (vlan ids, etc) from wherever the plugin stores it and serve that from the agent api along side the stuff stored in neutron.
3. Build a config in teeth-agent.