Support alternate I2C bus

Script should support alternate i2c bus , pretty simply addition 

requires 
```
pip3 install adafruit-extended-bus
```

and then small change to config 

```
from adafruit_extended_bus import ExtendedI2C
i2c = ExtendedI2C(4)  # Access I2C bus 4
```

However I am not sure how best to plug this into your installer so I figured best to start w/ issue 