md-list-item with ng-click and aria-label

```
<md-list-item ng-click="$state.go('customers-view', {'customerId': customer.customerId})"
                                  aria-label="View {{customer.firstName + ' ' + customer.lastName}}">
```

The md-list-item has a <button> underneath (generated by the directive) but it doesn't pass the aria-label.

http://codepen.io/anon/pen/JdYgYp
