Implement a set of functions to create messages following the protocols
defined in the README for communication.
Handle HID, which is used to communicate with the interactive application.
Update README with details on the message structures.
Add a new class to handle the RFID module and associated data
in order to track active tags.
Update main with RFID initialization and a minimal usage to
check it is working as expected.
pinMode most of what could be useful in the main and put modules
LOW to minimize power draw before the regulator is ON.
Add the skeleton for the setup, main loop and battery level checking.
