Starting to implement the proper HTML.

According to https://github.com/hakimel/reveal.js slides have to be nested like this:
```html
<div class="reveal">
	<div class="slides">
		<section>Single Horizontal Slide</section>
		<section>
			<section>Vertical Slide 1</section>
			<section>Vertical Slide 2</section>
		</section>
	</div>
</div>
```
(Markdown in commits!)