OpenContrail Nova VIF driver implementation

This blueprint is to add plugin for OpenContrail in existing Nova VIF
driver to support
OpenContrail based network virtualization for Openstack.

The OpenContrail APIs will cover following:

* Create Interface
* Delete Interface
* Get Interface Config

URL:
https://blueprints.launchpad.net/nova/+spec/opencontrail-nova-vif-driver-plugin
Change-Id: Ie1064486211ce60052177849250d1caf5d679dce
Merge "OpenContrail Nova VIF driver implementation"