Fix for setup script in Windows (#2480)

@mensae's work on fixing the setup script for Windows environments

Author: kazuma512

internals/scripts/helpers/get-npm-config.js

@@ -0,0 +1,3 @@
+const fs = require('fs');
+
+module.exports = JSON.parse(fs.readFileSync('package.json', 'utf8'));

internals/scripts/helpers/progress.js

@@ -1,20 +1,14 @@
-'use strict';
-
 const readline = require('readline');
 
 /**
  * Adds an animated progress indicator
  *
  * @param  {string} message      The message to write next to the indicator
- * @param  {number} amountOfDots The amount of dots you want to animate
+ * @param  {number} [amountOfDots=3] The amount of dots you want to animate
  */
-function animateProgress(message, amountOfDots) {
-  if (typeof amountOfDots !== 'number') {
-    amountOfDots = 3;
-  }
-
+function animateProgress(message, amountOfDots = 3) {
   let i = 0;
-  return setInterval(function() {
+  return setInterval(() => {
     readline.cursorTo(process.stdout, 0);
     i = (i + 1) % (amountOfDots + 1);
     const dots = new Array(i + 1).join('.');