Updates to PresentationBuilder 

- Adds support for code block nested in lists (Django-wiki does not support this and will produce the incorrectly formatted code, but Remark.js does; this includes a patch that does what is needed to perform the nesting)
- Added basic support for [Reveal.js](http://lab.hakim.se/reveal-js/#/) format, I think I would like to move to this eventually but there is quite a bit of work to do with styling to make it right.
- Adds the ability to disable slides by name, this was needed for the Outputs documentation which as far more content on the wiki then needed in the training materials

refs #4343