introduce os-vif VIF object for patch port pairs

Fix proposed to branch: master
Review: https://review.openstack.org/485228

As per description: until it's clear what request for enhancement is sought after on the neutron side, marking incomplete. That said, shouldn't this effort be more widely captured as 'adoption of os-vif in neutron', rather than tracking the individual vif types?

@Armando: you are right. The adoption of os-vif in Neutron should be tracked in a common place.

Because several type of VIFs are going to be be handled by os-vif and it's not a trivial change, I'll bring this topic to the Neutron's meetings to decide which should be the strategy to implement it.

Thanks for the recommendation.

Change abandoned by Rodolfo Alonso Hernandez (<email address hidden>) on branch: master
Review: https://review.openstack.org/485228