add reveal.js source from 55dceaaa

55dceaaa0a6fa02f76384046ae1ba0d792d7f1ef, to be precise.

https://github.com/hakimel/reveal.js/commit/55dceaaa0a6fa02f76384046ae1ba0d792d7f1ef

I excluded the test/ dir.
tidy, customize for my talk

used https://github.com/w3c/tidy-html5 / http://w3c.github.io/tidy-html5/