Driver based model for kuryr-libnetwork

[OpenStack Infra]

https://review.openstack.org/400365
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commit 09f11aa3945e1a0b24b8097941259bf21fdf4b03
Author: Marco Chiappero <email address hidden>
Date: Mon Nov 21 17:44:29 2016 +0000

    Driver based model for kuryr-libnetwork

    This patch introduces drivers to perform deployment specific functions
    for libnetwork. This patch is based on and complementary to the driver
    model introduced in kuryr-lib for port binding, by enabling its use in
    kuryr-libnetwork.

    Initially the following two drivers will be available and included:
    * veth: this driver will exclusively make use of the the corresponding
      kuryr-lib veth driver.
    * nested: this driver is intended for nested containers and will enable
      the use of ipvlan/macvlan binding drivers.

    The driver will be selected by means of a new 'port_driver' option.

    NOTE: Due to https://bugs.launchpad.net/kuryr-libnetwork/+bug/1651015
    When trying nested ports, it is important to use Kuryr to create the
    networks that will be used by Nova to create the instances, otherwise
    the nested ports will not be able to be cleaned.

    DocImpact
    Co-Authored-By: Luis Tomas Bolivar <email address hidden>
    Co-Authored-By: Louise Daly <email address hidden>
    Co-Authored-By: Gary Loughnane <email address hidden>
    Implements: blueprint driver-binding-ipvlan

    Change-Id: I380fb017dc97a2cd54a404ec3c8154ecc2df80b8