Code previews

- [x] Use [this](http://codepen.io/davatron5000/pen/tzJKh) to automagically generate code. Thanks to @graste for pointing it out. I was going to do it another way but this has the least maintenance involved.
- [x] Strip demo HTML classes from generated code
- [x] Style code blocks
- [x] Add code blocks to all components (where it makes sense to)
- [x] Add ability to copy code with a simple click using [ZeroClipboard](https://github.com/zeroclipboard/zeroclipboard)
- [x] Add feedback when clicking "Copy"

The `dataCodeBlock` plugin has a dependency on jQuery which is not ideal. A future PR could involve either rewriting it with vanilla JS or else doing a custom jQuery build which only contains the core code.