Dragging a folder to Upload Files locks Firefox when upload is attempted.

Only appears to be an issued with Firefox (29.0.1 on Mac OS X) but dragging a folder to the file upload drop zone and then clicking `Upload file(s)` locks the browser.

No errors in the console.
```javascript
oae.api.util.template().render($('#upload-body-template', $rootel), {
        'ios': oae.api.util.isIos()
    },
    $('.modal-body', $rootel)
);
```