Add the support for id and outputclass in Markdown

[jlacour31]

Description

Currently id and outputclass are only available in headings, this could be extended to elements like list-items or images. We should be able to keep the same format, something like

![Carrot](../../images/Carrot.jpg){#carrot .juice}

Workaround

At the moment the only solution is to embed HTML inside the md file:

<img src="../../images/Carrot.jpg" id="carrot" outputclass="juice">

[kirkilj]

Table classes have been requested by several of our R&D colleagues, who would like to standardize on a set of different table styles.

Codeblock is another to indicate syntax coloring styles