Add PiGatewaySerial draft

Signed-off-by: Tomas Hozza <thozza@gmail.com>
Add signal handler

Signed-off-by: Tomas Hozza <thozza@gmail.com>
Implement the serial interface for Gateway

Signed-off-by: Tomas Hozza <thozza@gmail.com>
Build the PiGatewaySerial

Signed-off-by: Tomas Hozza <thozza@gmail.com>