[api] Slide. TemplateFinder. WIP.
[templates] Rough draft of sample templates

..to be used programmatically.
[slide] #html produces html
[presentation] is a collection of slides

Slides are ducks that responds to ".html"
[templates] Update code: no escaping
[api] SlidesHtmlBuilder can create slides.html
[api] Presentation can capture theme, author, etc

It now fulfills the 'duck type' of being a RevealCK::Config.
[api] Refer to bundled reveal.js files in variable

Now RevealCK (the module) has the burden of understanding this
knowledge, and reveal-ck (the executable) does not.
[api] PresentationBuilder now builds from Presentations
[api] Presentations now have a default theme
Programmatic support for building Slides

There are now classes like 'Presentation' and 'Slide' and you can do
something like,

```
p = Presentation.new
first_slide = Slide.new
second_slide = Slide.new
p.add_slide first_slide
p.add_slide second_slide
```

And sooner or later end up with a reveal.js presentation somewhere on
your file system.
[templates] Minor slide template changes
[slides.rb] Load Presentation stuff from file
[slides.rb] SlidesHtmlBuilder now works with slides.rb
[slides.rb] reveal-ck now supports slides.rb
[slides.rb] Packages templates/ in gem
Support slides.rb: a dsl-ish for slides