Adding assert for type and tag

Implements `assertWrappedElement` to check for correct wrapped element in typified elements.

Closes #53 
With the new added role we have the following elements would match:

```html
<button>
<input type="button">
<input type="submit">
<div role="button">
```

It makes sense to test all three cases, although I test the failing attribute indirectly through the role criterion.