add yum-plugin-priorities package

To manage repo priorities, we need to add this package.
openstack-full: add yum-skip-broken

yum-skip-broken will be used to ignore dependency on nova-compute.
openstack-full: ensure nova-compute is installed without issue
openstack-full: install nova-compute without deps
purge qemu-rhev before installing ceph package
force to install qemu from ceph repo
openstack-full / RHEL: Install KVM / Qemu from Ceph repository

Install qemu-kvm without breaking nova-compute.