As seems impossible (or at least not easy) to have a single Vagrantfile
with suitable configuration for different backends, this commit add two
backend-specific Vagrantfile.
It's up to the user to choose which to symlink (or copy) to `Vagranfile`
before running vagrant.
- Rename Vagrantfile to Vagrantfile.vbox
- Add Vagrantfile.libvirt
- Add libvirt specific provision script
- Add 'Vagrantfile' to gitignore
