Fix hardcoded topic strings with constants.

Replace hardcoded topic strings like 'volume' or 'compute'
with config constants like FLAGS.volume_topic, etc. See
bug #1057831 and bug #1061628.

Change-Id: I817ecc3cbe3245b51a0c047be58d17edfec8a838

bin/nova-network

@@ -41,8 +41,10 @@ from nova import utils
 
 if __name__ == '__main__':
     flags.parse_args(sys.argv)
+    FLAGS = flags.FLAGS
     logging.setup("nova")
     utils.monkey_patch()
-    server = service.Service.create(binary='nova-network')
+    server = service.Service.create(binary='nova-network',
+                                    topic=FLAGS.network_topic)
     service.serve(server)
     service.wait()