title: IONIC2 not display image from assets on device
body: <p>my image (640x 360)
  my sclass</p>
  
  <pre><code>.auth-home {
  background-image: ('./assets/img/auth-background.jpg'); 
  background-size: 100%;
  background-position-y: 50%;
  }
  </code></pre>
  
  <p>i try set background-image:</p>
  
  <ul>
  <li>background-image: ('assets/img/auth-background.jpg') no-repeat center center fixed;</li>
  <li>background-image: ('../assets/img/auth-background.jpg') no-repeat center center fixed; </li>
  <li>background-image: ('./assets/img/auth-background.jpg');</li>
  </ul>
  
  <p><strong>but ONLY device not display</strong></p>