Replace guggenheim with reveal

I had trouble with Reveal trying to find a home slide using `document.querySelector('.reveal .slides>section:first-child')`, which would fail to find anything and then everything goes haywire. I modified reveal.min.js to not include the `:first-child` bit, and that works.

I'm also seeing quite a few `Invalid CSS property name:` messages in the log. I'm guessing these are properties that aren't available in `node-webkit`. Everything seems unstyled but functional, regardless.

Lastly... when it gets to the end, it loops back. I mean, like the top of a typewriter. If you cycle through the games in one direction, it will loop (the loop option is enabled) but it visually jumps backward once to get to the beginning. 

But all in all, this works fine on my machine.