Create a GPIO subsystem for signaling when middleware board is ready

[domiwskakuj]

It is difficult to say currently when the board has successfuly turned on and started working. A simple diode and autoload should be enough to signal readiness.

• diode signaling finished boot
• diode signaling connection to internet
• diode signaling bluetooth server activation
• diode signaling serial port communication state
• diode signaling emptiness/fullness of packet queue