Add some example scripts to load with webpack

The example JS files demonstrate
 * The use of CommonJS dependency management syntax[1]; 'require' and
'module.exports' statements
 * Using webpack to require dependencies that (for whatever reason) are
in the global scope
 * Using ES6 features in your JS (relying on the ES6-loader to polyfill
your code)
 * Using sprockets to load JS bundled by webpack as well as JS from gems
(in this case just the default Rails jquery gem

app/assets/javascripts/_application.js

@@ -0,0 +1,2 @@
+// files required here will run in the global scope
+require('./hello_world');

app/assets/javascripts/application.js

@@ -13,4 +13,4 @@
 //= require jquery
 //= require jquery_ujs
 //= require turbolinks
-//= require_tree .
+//= require main.bundle

app/assets/javascripts/hello_world.js

@@ -0,0 +1,8 @@
+var $ = require('jquery'),
+    HelloWorldView = require('./views/hello_world_view');
+
+// Any logic to initialize the app goes here
+// For example, starting any routers or initializing the 'home' view
+$(function() {
+  HelloWorldView.render();
+});

app/assets/javascripts/views/hello_world_view.js

@@ -0,0 +1,22 @@
+var $ = require('jquery');
+
+var firstPar = $('<p>'),
+    textStart = $('<span>').text("You're using "),
+    webpackURL = 'http://webpack.github.io/',
+    webpackLink = $('<a>').attr('href', webpackURL).text('webpack'),
+    textEnd = $('<span>').text(' with Rails.'),
+    es6text = 'ES6',
+// The ES6 loader will compile this template string into the ES5 equivalent.
+    es6Par = $('<p>').text(
+      `You can also use ${es6text} features with the ES6 loader.`
+    );
+
+firstPar.append(textStart).append(webpackLink).append(textEnd);
+
+var HelloWorldView = {
+  render: function() {
+    $('.main').append(firstPar).append(es6Par);
+  }
+};
+
+module.exports = HelloWorldView;