Add join_consumer_pool() to RPC connections

blueprint move-listener-framework-oslo
bug 1047015
bug 1111632

Ceilometer and Quantum use private methods of the RPC connection
object to configure themselves to listen to a queue shared among a
group of workers. This change adds a public method to the RPC
connection to support this use case, without resorting to using
private API calls.

Change-Id: I3a89f1dfdcf8accca70cf305f7a31315bea093d8
Signed-off-by: Doug Hellmann <doug.hellmann@dreamhost.com>
Cleanup imports

Bringing this into Nova, I found that it
failed their pep8 checks (which are NOT
ignored for the oslo imported binaries)

Change-Id: I4fb7e32bc7e83faf4131302a06c4d9c2c16cab70
Merge "Cleanup imports"
Merge "Add join_consumer_pool() to RPC connections"