Add support for setting extra network options for ML2 plugin

[Kyle Mestery]

The ML2 plugin is deprecating support for the OVS and LinuxBridge plugins at some future point. The plugin works with the existing OVS and LinuxBridge agents. Adding support to devstack to configure extra options (similar to how this was done for LinuxBridge and OVS [1]) would be a nice addition for developers of ML2.

[1] https://review.openstack.org/#/c/30315/14

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/37963

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/37963
Committed: http://github.com/openstack-dev/devstack/commit/b772659f9df8153caa3b0fa155614d2d6504541e
Submitter: Jenkins
Branch: master

commit b772659f9df8153caa3b0fa155614d2d6504541e
Author: Kyle Mestery <email address hidden>
Date: Fri Jul 19 14:26:53 2013 +0000

    Update the ML2 configuration in devstack

    This commit adds support to devstack to set ML2 options including
    MechanismDrivers, TypeDrivers, and TypeDriver specific configuration for ML2
    when running with devstack.

    This also allows for simple configuration of VLAN, GRE, and VXLAN ML2 devstack
    setups with the OVS agent as follows:

        # VLAN configuration
        Q_PLUGIN=ml2
        ENABLE_TENANT_VLANS=True

        # GRE tunnel configuration
        Q_PLUGIN=ml2
        ENABLE_TENANT_TUNNELS=True

        # VXLAN tunnel configuration
        Q_PLUGIN=ml2
        Q_ML2_TENANT_NETWORK_TYPE=vxlan

    Fixes bug 1200767

    Change-Id: Ib16efac13440b5d50658a0e6be35bc735510a262