First pass to figure out OO structure

Please take at this effort to make this app OO.

- Is the structure OK with the MBCRegistrationEmailController::SubscribeToMailChimp($channel, $config) call?
- Does it make sense to use the SubscribeToMailChimp method as a controller (if that's the right term)?
- Are the calls to setupExchange() and setupQueue() in CollectNewRegistrations() making sense?