virtio claims to bring some additional performance

- add some custom variables that can be set on top of script
- use bridge=br0 instead of network=default

We need to set a serial console to our guest kernel so virsh can interact with it.
Keep in mind we have systemd on recent systems, which eases the setup

    edit /etc/default/grub
    add console=ttyS0 to the cmdline for booting
    update-grub

see http://0pointer.de/blog/projects/serial-console.html

- serial console "everywhere"
- dynamic NAT bridge (needs improvement)
- storage on lvm