Open Stack

I've pushed out a review [1] to enable support for setting additional ML2 options when running with devstack. Since H2, ML2 has now added support for both GRE and VXLAN tunnels, and the patch below allows for this configuration when running with devstack. Feedback from folks on the Neutron ML2 sub-team and devstack developers would be appreciated!

Thanks!
Kyle

[1] https://review.openstack.org/37963