Update server.js with E6 syntax (#101)

server.js updates tested and validated here: https://boilerplate-express.johnsprunger.repl.co

Co-authored-by: Muhammed Mustafa <MuhammedElruby@gmail.com>

server.js

@@ -3,15 +3,15 @@
  * the verification process may break
  * ***************************************************/
 
-var bGround = require('fcc-express-bground');
-var myApp = require('./myApp');
-var express = require('express');
-var app = express();
+const bGround = require('fcc-express-bground');
+const myApp = require('./myApp');
+const express = require('express');
+const app = express();
 
 if (!process.env.DISABLE_XORIGIN) {
-  app.use(function(req, res, next) {
-    var allowedOrigins = ['https://narrow-plane.gomix.me', 'https://www.freecodecamp.com'];
-    var origin = req.headers.origin || '*';
+  app.use((req, res, next) => {
+    const allowedOrigins = ['https://narrow-plane.gomix.me', 'https://www.freecodecamp.com'];
+    const origin = req.headers.origin || '*';
     if(!process.env.XORIG_RESTRICT || allowedOrigins.indexOf(origin) > -1){
          console.log(origin);
          res.setHeader('Access-Control-Allow-Origin', origin);
@@ -21,8 +21,8 @@ if (!process.env.DISABLE_XORIGIN) {
   });
 }
 
-var port = process.env.PORT || 3000;
-bGround.setupBackgroundApp(app, myApp, __dirname).listen(port, function(){
+const port = process.env.PORT || 3000;
+bGround.setupBackgroundApp(app, myApp, __dirname).listen(port, () => {
   bGround.log(`Node is listening on port ${port}...`);
 });