Arduboy bootloader with RGB LED test

I've adapted the caterina bootloader so it flashes the RGB LED during a 7.5 second timout.

[@Davedarko]

Is that a 2.7 inch oled? Nice

[@MrBlinky]

davedarko it's a 2.42" one.

[@Davedarko]

wait what :D I just wrote that on twitter and forgot about this comment here :D