Support for Docker Machines.

Allow for a new tree view of docker machines via the docker-machine command. From here we could gather statistics on our host machines. We could start/stop/restart/rm and SSH into them as needed.

This would also allow for us to select a docker machine and then have the rest of the containers/images tree views filtered by that machine only. Be helpful to filter/manage local for remote docker hosts.

Thoughts on this one? I now a bit more involve but i think it would be really helpful to have.