Consumer-related progress.

- Renamed test script to consume.py .
- Command object now takes connection object rather than socket.
- We now pass a message-queue to the connection object to enqueue incoming messages.
- Renamed send_message to send_command.
- We now return control to the caller of the client, but only after one connection is established.
- Connection objects now have an is_connected property.
- We now start a message-handler greenlet.
- We moved the connections list to being an object field (of the client).
- We now provide a "terminate" event so that our caller can determine if the client has died.
- Squelched some of the "making a connection" logging messages.