Feature Request: Add OpenStack provider.

[smathermather]

If I wanted to add an OpenStack provider, I would just discern the appropriate template based on the divers in docker-machine, I think.

https://github.com/docker/machine/blob/master/drivers/openstack/client.go

Is this the approach?

[pierotofy]

Will close this since there's been no progress (PR still welcome of course).