Add simple EEPROM implementation for RPi

This implementation provides EEPROM like
storage for information. Its size is 1KB.
It provides the same functions as on AVR
and as used by MySensors.

Signed-off-by: Tomas Hozza <thozza@gmail.com>
Use PiEEPROM for EEPROM operations

Signed-off-by: Tomas Hozza <thozza@gmail.com>
Implement PiGatewaySerial with TTY interface.

Implement MySensors Gateway for RPi with TTY
interface using PTY - pseudo terminal.

After starting it creates a MySensors GW and
PTY, in /dev/pts/ which is then symlinked to
/dev/ttyMySensorsGateway

It also handles SIGINT.

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

Signed-off-by: Tomas Hozza <thozza@gmail.com>
Merge pull request #4 from thozza/master

Add EEPROM implementation for RPi and Gateway with TTY interface for RPi