Open Stack

Hello, devstack!

I want to draw some attention to the fact, that install_libvirt function
now (since https://review.openstack.org/#/c/438325 landed)
only works for Centos 7, but not for other RHEL-based distributions:
Virtuozzo and, probably, RHEV.

Both of above have own version for qemu-kvm package: qemu-kvm-vz and
qemu-kvm-rhev,
accordingly. These packages provide "qemu-kvm", like qemu-kvm-ev,
and, when you call "yum install qemu-kvm", they replace the default OS
package.

To solve this, I propose install by "qemu-kvm" name, like in the patch:
https://review.openstack.org/440353