This fixes the collector part of the bug 1075463.
Declaring a consumer topic on the same rpc connection after the consume
thread has started would result the eventlet raise RuntimeError
exception. So all the declaring work should be done before calling
rpc.conn.consume_in_thread().
Using the hook 'initialize_service_hook()' provided by rpc.Service in
oslo to decalre the collector's specific topic consumers before starting
the consuming thread.
Change-Id: I33a98c228d45f7716e46d40d9203188f4e827c11
2b30965869