etherport option for firmata.js repl

repl.js

#!/usr/bin/env node

const firmata = require("./lib/firmata");
const Etherport = require("Etherport");
const repl = require("repl");
console.log('Enter USB Port or "etherport" and press enter:');
process.stdin.resume();
process.stdin.setEncoding("utf8");
process.stdin.once("data", (chunk) => {
  chunk = chunk.replace("\n", "");
  const port = ("etherport" === chunk) ?  new Etherport(3030) : chunk.replace("\n", "");
  const board = new firmata.Board(port, () => {
    console.log(`Successfully Connected to ${port}`);
    repl.start("firmata>").context.board = board;
  });
  board.on("string", msg => console.log(`Board message: ${msg}`));
});