RFM2Pi Gateway as a daemon

Hi.

I believe these commits address our concerns in https://github.com/emoncms/raspberrypi/issues/5 (Daemonize raspberry_run.php). See comments on that issue record.

What's new: 

- RFM2Pi Gateway (the python one) is daemonized
- The web GUI has the power to start/stop the script and read the logs for a live display

Both features require manual configuration, detailed in the readme file.

https://github.com/emoncms/raspberrypi/pull/12 (dropdown menu for remoteprotocol) is already merged in.

Please tell me what you think and ask for rework if it is unfit for integration.