* Some further changes for python2 vs python3 packages
* Allow rabbitmq 3.7.*, since a newer erlang is available
* Switch from qemu-img-ev to qemu-img on CentOS 8
* bridge-utils no longer available on CentOS 8
* libvirt-daemon-driver-lxc no longer available on CentOS 8
* Mark some more images buildable for CentOS 8
Change-Id: Iaf5b68ff6d944ae730ca0b1d5832172c106a6c08
Partially-Implements: blueprint centos-rhel-8
Partially-Implements: blueprint centos-rhel-python-3
4b4e26262b