Better document that we cannot use RaspberryGpioInterface but RaspberryGpioDaemonInterface

[marianopeck]

We should explain better that in VAST, we can only use RaspberryGpioDaemonInterface so far and that RaspberryGpioInterface crashes the VM. We should put that as class comments or even rename RaspberryGpioInterface to RaspberryGpioInterfaceBROKEN or move it to a separate subclass or something. In addition, we can implement RaspberryGpioInterface class >> raspberryGpioStart doing a self error: 'not supported... use daemon instead....