reveal-ck is now an executable

## Overview

Initially, I thought people might check out this project (jedcn/reveal-ck) and, amidst all of the pieces that go into developing reveal-ck (a spec dir, a features dir, Gemfiles, a git submodule to reveal.js itself, etc) they would home in on a ```slides.haml``` and start modifying it.

I tried this myself, and I found all of the non-slide stuff distracting. The point of this project is to be "alone" with the essence of your presentation, and something had gone wrong. Anyway, reveal-ck is now a gem that brings a command line executable with it of the same name.

For end users of reveal-ck, the Gemfile isn't included and bundler is up to them, the spec and features directories aren't present, and the reveal.js stuff is packed inside of the gem.

To make sure I was going in the correct direction, I back-ported a talk I had done previously, jedcn/talk-learning-with-rspec to this new format and it ended up pretty close to where I wanted to be (just a straight up ```slides.haml``` and my images. Actually, now that I look,   there's a bunch of junk there, but the majority needs to be extracted out into a 'How to use RevealCK' page.)

## Actual Changes

* It's now a gem, managed by jeweler
* davetron5000/gli is used for cli support. Jeweler version stuff takes precedence over gli stuff (say, for managing the gemspec)
* Basic "acceptance" tests are done in Cucumber.

## Bottom Line

Once you have the gem, you can run ```reveal-ck generate``` in any directory that has a ```slides.haml``` and this gem will build up a reveal.js presentation based on the ```slides.haml``` at ```slides/index.html```

Things you can and can't do:
- [x] You **can** include an ```images/``` directory underneath your ```slides.haml``` and these images will be copied into ```slides/``` and available for your presentation to reference.
- [ ] You **cannot** customize anything in the reveal.js, likes colors or themes.
- [ ] You **cannot** tweak the CSS.