automate provisioning of lxc network and debian host

I submitted this PR to get early feedback, this is work-in-progress and not functional yet. The goal is to turn `lxc.md` into something actionable and executable. I aim to provide 2 things:

* A Vagrantfile to create a debian testing host as a VM
* Auto-configuration of lxc containers to run jepsen tests out-of-the-box

Is this interesting/valuable/useful? Wondering whether this might not warrant a dedicated repo...