Adafruit Circuit Playground Test

[HipsterBrown]

I tested the recent release of avrgirl-arduino with support for the Adafruit Circuit Playground Classic against the board.

Result:

hipsterbrown:avrgirl-arduino (master) $ node tests/demos/circuit-playground-classic.js
found circuit-playground-classic on port /dev/cu.usbmodem1421
resetting board...
reset complete.
connected
flashing, please wait...
flash complete.
done.
hipsterbrown:avrgirl-arduino (master) $

Success!!! 🎉

This PR adds a test demo file for the circuit-playground-classic and updates the README to include the board in the supported boards list (I also added myself to the list of contributors if this is approved).

[coveralls]

Coverage remained the same at 44.84% when pulling 85eff9a on HipsterBrown:circuit-playground-test into 53bf0a5 on noopkat:master.

[noopkat]

Thank you so much @HipsterBrown for testing and writing code / docs for this board. Merging! 🙌🏻