title: How to add shadow to the FAB provided with the android support design library?
body: <p>The title is pretty self explaining.</p>
  
  <p>The following code does not render shadow below the Floating Action Button. What can be done to render shadow? Is this feature really not supported even on API 21+?</p>
  
  <pre><code>&lt;android.support.design.widget.FloatingActionButton
      android:layout_height="wrap_content"
      android:layout_width="wrap_content"
      android:src="@drawable/ic_add"
      android:clickable="true" /&gt;
  </code></pre>
  
  <p>Note: Adding <code>android:elevation</code> does not add shadow on API 21.</p>
  
  <p><img src="https://i.stack.imgur.com/Wb28n.png" alt="Example screenshot"></p>
  
  <p>Screenshot taken from the example by dandar3:
  <a href="https://github.com/dandar3/android-support-design">https://github.com/dandar3/android-support-design</a></p>