Pin-Header changes in Rev2

According to http://elinux.org/RPi_Low-level_peripherals#General_Purpose_Input.2FOutput_.28GPIO.29 there has been more than one change in Rev2 concerning the GPIO-Pins.

Currently /src/quick2wire/gpio.py has only this:
```
if revision()>1:
    RaspberryPi_HeaderToSOC[13] = 27
```

But according to the link provided above, this should probably read:
```
if revision()>1:
    RaspberryPi_HeaderToSOC[3] = 2
    RaspberryPi_HeaderToSOC[5] = 3
    RaspberryPi_HeaderToSOC[13] = 27
```