title: Require Vue from JS file
body: <p>i'm pretty new to modern frontend development tools.
  I installed Nodejs and NPM. Downloaded some packages (es: "jquery") and everything worked. Then I installed Webpack (vers. 2), I created this demo config file</p>
  
  <pre><code>module.exports = {
     entry: "./entry.js",
     output: {
         path: __dirname,
         filename: "bundle.js"
     }
  };
  </code></pre>
  
  <p>In my JS entry point (entry.js) I can successfully use jQuery module, as follows</p>
  
  <pre><code>var $ = require("jquery");
  $('#test').html('Changed!');
  </code></pre>
  
  <p>Everything works fine.
  The problem arises when I go for Vue. I install it</p>
  
  <pre><code>npm install vue --save
  </code></pre>
  
  <p>And then use it</p>
  
  <pre><code>var Vue = require("vue");
  var app = new Vue({
      el: '#app',
      data: {
          message: 'Hello Vue!'
      }
  });
  </code></pre>
  
  <p>I don't know how to import and then use the constructor. What I wrote clearly cannot be right! In fact I get this error</p>
  
  <pre><code>TypeError: Vue is not a constructor
  </code></pre>
  
  <p>What am I missing?
  (NOTE: I am not using any other tool, only Nodejs + NPM + Webpack2 and I would like to keep going using only these three, if possibile).</p>
  
  <p>Thank you,
  Marco</p>