Feature request: Send messages to the LED sign, sound an alert

[cjdavis]

Add a command that will send messages to the scrolling LED display currently mounted above the bar.

Also would like some sort of bell, buzzer, etc. so people actually know to look at the display.

There is a serial cable attached to the display now, there are a couple of options for its connection:

1. The open switch arduino.
   Pros - no extra daemon / computer needed
   Cons - Level shifters may be required, as well as a rudimentary driver.
2. A machine - like filestor, glassy..
   Pros - Linux driver already written, could do fancy stuff?
   Cons - Another daemon / driver would need to run