Add notify option to order confirm function

The confirm function in catalog/model/checkout/order.php forces an email to be sent. Would be better to add the option to NOT send the email so that customized emails can be controlled by the payment system. There is currently no good way now to prevent the confirmation step from sending out an email without copying it to your local file and referencing that one. Would be easier if we could add a 'false' at the end.

Change:
public function confirm($order_id, $order_status_id, $comment = '') {

to:
public function confirm($order_id, $order_status_id, $comment = '', notify = true) {

and add a conditional around the email call

I have to agree with this one, would be nice.