Render list with multiple nodes on the first level

Hello,

Currently, only the first li of a list is displayed with jOrgChart.
With this commit, every nodes from the first level will be drawn without a parent
on the first line of the graph with a list like :
```html
<ul>
  <li>First</li>
  <li>Second
    <ul>
      <li>Sublevel</li>
    </ul>
  </li>
</ul>
```