em-checkbox cannot be disabled

[josefguenther]

Specifying disabled on an em-checkbox component does not produce the desired effect.

{{em-checkbox label="Check this" property="checkThis" disabled="disabled" }}

Produces this:

<div class="ember-view checkbox" disabled="disabled" id="ember1098">
  <label class="ember-view control-label" for="checkThis-ember1098" id="ember1101">
    <input class="ember-view" id="checkThis-ember1098" type="checkbox">
    Check this
  </label>
</div>

As you can see, the disabled attribute is set on the parent DIV but not on the INPUT. On a normal em-input, it is set on both the div and the input, and works correctly.

[spruce]

Thanks for catching that! Do you wanna create a PR?