figure and figcaption not supported

[mtabasco]

Hi! Just testing with Osmosis but it seems it doesnt support FIGURE nor FIGCAPTION tag elements.
Example code:

<p class="md-block-unstyled">caption1</p>
  	<figure class="md-block-image">
      <img src="https://github.githubassets.com/images/modules/logos_page/GitHub-Mark.png" alt="" />
      <figcaption class="md-block-image-caption">Github</figcaption></figure>
<p class="md-block-unstyled">
 	 <br/>
  	</p>

It seems libxmljs doesnt support that tags. Is there any workaround for handling them?

thank you!