[READY] Adding single byte read/writes from eeprom

Adds the following API for reading and writing bytes:


```.js
// Read multiple bytes
avr.readEEPROM(numToRead, startAddress, callback(err, bufferRead);

// Write multiple bytes
avr.writeEEPROM(byteArr, startAddress, callback(err));

// Read a single byte
avr.readEEPROMByte(address, callback(err, byteRead)); // callback(err, byteRead)

// Write a single byte
avr.writeEEPROMByte(byte, address, callback(err));

```

Binding `byteArr` and passing it as an arg shouldn't be necessary, but it doesn't hurt either.