New configuration strategy needed to adapt to oslo-messaging

oslo messaging use oslo.config as configuration utility to setup Transport object. Here are 2 problems need to consider:
1)
oslo.messaging: parse options in the default section as amqp paramerters input
our current design: 2 message brokers to setup, options are parsed from [openstack] and [powervc] sections respectively.
2)
oslo.config.cfg.CONF is a single global configuration options container shared in a process.

A new configuration strategy is needed to solve the 2 problems.

Here is one proposal:

1. devide powervc.conf into powervc.conf, amqp-powervc.conf, amqp-openstack.conf.
2. all amqp related options in both [powervc] and [openstack] sections of powervc.conf will be removed.
3. all amqp related options for powervc are configured in amqp-powervc.conf.
4. all amqp related options for openstack are configured in amqp-openstack.conf.
5. at the beginning of a driver service launching,
  5a. initialize and parse for an oslo.config.cfg.ConfigOpts object with amqp-powervc.conf and save as amqp_powervc_conf.
  5b. initialize and parse for an oslo.config.cfg.ConfigOpts object with amqp-openstack.conf and save as amqp_openstack_conf. for neutron-powervc-agent there is a little difference due to control_exchange setup, currenlty we use another conf amqp-openstack-neutron.conf specifically instead of amqp-openstack.conf.
6. remove the two amqp conf file from the sys.argv list
7. then initialize and parse for the global oslo.config.cfg.CONF with powervc.conf and other confs like nova.conf, cinder.conf..
8. when create transport oslo.messaging.Transport, use corresponder amqp conf.

The new service launching commands are:

Glance:
python glance-powervc/bin/glance-powervc --config-file /etc/powervc/amqp-openstack.conf --config-file /etc/powervc/amqp-powervc.conf --config-file /etc/powervc/powervc.conf --logfile /var/log/powervc/glance-powervc.log

Neutron:
python neutron-powervc/bin/neutron-powervc-agent --config-file /etc/powervc/amqp-openstack-neutron.conf --config-file /etc/powervc/amqp-powervc.conf --config-file /etc/powervc/powervc-neutron.conf --config-file /etc/powervc/powervc.conf --logfile /var/log/powervc/neutron-powervc.log

Cinder:
python cinder-powervc/bin/cinder-powervc --config-file /etc/powervc/amqp-openstack.conf --config-file /etc/powervc/amqp-powervc.conf --config-file /etc/powervc/powervc.conf --config-file /etc/cinder/cinder.conf --logfile /var/log/powervc/cinder-powervc.log

Nova:
python nova-powervc/bin/nova-powervc --config-file /etc/powervc/amqp-openstack.conf --config-file /etc/powervc/amqp-powervc.conf --config-file /etc/powervc/powervc.conf --config-file /etc/nova/nova.conf --logfile /var/log/powervc/nova-powervc.log