Ensure form is submitted via jquery trigger

I wanted the submission of the form to be handled using an ajax approach using jQuery. To do this I just needed to make a simple change so that the submission of the form is triggered using jQuery.

For anyone else that is trying to achieve the same result, the glue code that I used to tie this all together (which uses [ajaxForm](http://malsup.com/jquery/form/)) is as below:

```javascript
var options = {
    success:  function(responseText, statusText, xhr, $form) {
		$('#facebook_container').remove();
		$('#fb-login-form').html(responseText);
	}
};
$('#fb-login-form').ajaxForm(options);
```

ps. Please ignore 2bb257b and the subsequent revert in 484ad0d - I decided to submit a separate pull request for that.