Final changes

Hi Tobias,

My final version, not going to make any modifications, only bug fixing if needed :)
Main changes: 
* removed hardcoded dependency on I2C bus, not MMR-70 can be connected to P5 header of RPI rev2
* removed hardcoded RDSINT pin number - added it to config file to be able move wires around without recompilling FMBerry
* added new command 'set stereo on|off' just for fun
* added to configuration pin to control LED if LED mod is applied
* updated HARDWARE and README files to reflect latest changes

Regards,
Andrey