Move libvirt's qemu configuration dir to state fs

We need libvirt domain entries created by Nova in to persist across
image upgrades.  Otherwise, instances are effectively removed from the
hypervisor after a new image deploys with an empty libvirt config tree.
This registers /etc/libvirt/qemu as a stateful path and ensures persistent
domain configurations across upgrades.

Change-Id: I419bb25069314c7e639f980b5c236711b2d58edc
Closes-bug: #1336115
Passthrough-enable for nova-<service>.conf

This permits passhthrough settings to be applied to
nova-<service>.conf. The idea is that under the 'nova' key in the
config we can specify specific service key for defining configuration
for each service.

Here an example of a heat config template that allows configuration for
nova-scheduler service in addition to the general nova config section:
{
  "nova": {
      "scheduler_config": [
            {"section": "DEFAULT",
             "values": [
                {
                   "option": "rpc_thread_pool_size",
                   "value": "2"
                 }
             ]
            }
      ],
      "config": [
            {"section": "DEFAULT",
             "values": [
               {
                   "option": "enable_new_services",
                   "value": "True"
               }
            ]
           }
        ]
    }
}

This depends on https://review.openstack.org/97785
blueprint: passthrough-config

Change-Id: I16ddffb650c66da30652e6abbc0ef5fca378ae70
Rename mariadb-rdo to mariadb-rpm

* mariadb-galera-cluster is now in fedora repositories so there is no need
to install it from RDO repository. This patch removes dependency on RDO repository.

* same package set should be also available in rhel and centos repositories soon
(after adding proper channels/repositories), so it makes sense to rename
it from '-rdo' to '-rpm'.

Change-Id: I90e7ca4803516b86179b0f6639e307a60297960b
Merge "Move libvirt's qemu configuration dir to state fs"
Merge "Passthrough-enable for nova-<service>.conf"
Merge "Rename mariadb-rdo to mariadb-rpm"