title: use webpack with vue, but require seems not working
body: <p>I use webpack to bundle js, sample:</p>
  
  <pre><code>var Vue = require('vue')
  
  var app = new Vue({
      el: '#app',
      data: {
          info: { email: '' },
          email: ''
      },
  
      methods: {
  
          onSignin: function (e) { },
      }
  })
  </code></pre>
  
  <p>use Webpack to generate a bundle and include it in html, got error:</p>
  
  <pre><code>test3b.js:7019 Uncaught TypeError: Vue is not a constructor(…)
  </code></pre>
  
  <p>any idea what missing here? thanks,</p>