Don't truncate object tags

`object` tags (with nested `param` and `embed` tags) should not be truncated, since the end result was an empty `object` tag.  For example, this YouTube embed tag...

    <object width="420" height="315">
      <param name="movie" value="//www.youtube.com/v/txqiwrbYGrs?version=3&amp;hl=en_US">
      <param name="allowFullScreen" value="true">
      <param name="allowscriptaccess" value="always">
      <embed src="//www.youtube.com/v/txqiwrbYGrs?version=3&amp;hl=en_US" type="application/x-shockwave-flash" width="420" height="315" allowscriptaccess="always" allowfullscreen="true"></embed>
    </object>

... was being returned in the truncated output as ...

    <object width="420" height="315">   </object>

I've updated the parsing to pass through `object` tags intact without parsing the tag contents.

Feel free to suggest a more robust approach.