Node identification

Each node has a unique id so user can refer to it during configuration
- based on the ratio of two resistors
- dip switch
  - convert 8 switch position into a number from 0 to 256
  - communicate number to AtMega (one wire bus)
- Flash chip has a 4 bytes unique identifier
~~Each node uses the same code binaries so it need to be configurable~~
- Not sure moteino's have enough memory for that
- Increase complexity