Fix auto_html does not render link and image separated by HTML tag correctly

Currently, if you have an HTML text with link and image separated by a div or a br, the resulting text is broken.

i.e.
```Website: http://www.google.com<br/>http://rors.org/images/rails.png```

compiles to

```Website: <img src="http://www.google.com%3Cbr/%3Ehttp://rors.org/images/rails.png" alt=""/>```

instead of

```Website: <a href="http://www.google.com">http://www.google.com</a><br/><img src="http://rors.org/images/rails.png" alt="">```

This commit solve this issue.