Replace oslo.rpc by oslo.messaging

The patch replaces oslo.rpc by oslo.messaging.

The important changes:
- On the collector, the queue name and the topic are now the same
  (ie: metering, instead of ceilometer.collector.metering for the queue
  and metering for the topic)
- Same for the alarm partitionner the queue is no more prefixed by
  ceilometer.alarm.

Implements switch-to-oslo.messaging

Change-Id: Ia5e4ff1dd1d419c090b8039627234ae7f07e8660