make libvirt module work under Fedora
make libvirt a system user
only create group, not user
regenerate config files if they are missing

This makes sure that libvirtd.conf and qemu.conf are regenerated
if they have been removed.
Updated README to reflect testing on Fedora
require package per suggestion from Keb Barber
made centos work like fedora
Merge pull request #1 from ghost/larsks

Make libvirt module work under Fedora