Many users, who admin their own machines, want to be able to access
system libvirtd via tools like virt-manager without having to enter
a root password. Just google 'virt-manager without password' and
you'll find many hits. I've read at least 5 blog posts over the years
describing slightly different ways of achieving this goal.
Let's finally add official support for this.
Install a polkit-1 rules file granting password-less auth for any user
in the new 'libvirt' group. Create the group on RPM install
https://bugzilla.redhat.com/show_bug.cgi?id=957300
