Crash the app or reconnect when connection is lost to the message broker

[AlexGustafsson]

Just as with #3, the App Delegate has error handling for when the connection to the message broker is lost. Currently the error is just logged. Proper error handling should be implemented to either crash the app or try to reconnect.

This seems to occur relatively often when running an application, resulting in no executor being registered.

self.connection.interruptionHandler = {
      logger.info("Disconnected from broker (interrupted)")
    };

    self.connection.invalidationHandler = {
      logger.info("Disconnected from broker (invalidated)")
    };