Wrapping stacked checkables in a div with their type

Stacked BS3 checkables [should be like](http://getbootstrap.com/css/#forms-controls):

```html
<div class="checkbox">
  <label>
    <input type="checkbox" value="">
    Option one is this and that&mdash;be sure to include why it's great
  </label>
</div>
```

This wraps non-inline checkables in a div with a the checkable type right before the checkable is created.  And adds tests for it.

It also adds some tests for setting checkables to disabled.