Give the possibility to modify the PDF filename

[Elyos59]

Add 3 variables in PdfEvent :

* @param string $templateName
* @param string $fileName
* @param string $object

Add default values to this variables in BaseController before dispatch event :

$pdfEvent->setTemplateName($fileName);
$pdfEvent->setFileName($order->getRef());
$pdfEvent->setObject($order);

Now in event listener, we have the possibility to modify Pdf filename.

For example :

TheliaEvents::GENERATE_PDF => ['generatePdf', 256],

public function generatePdf(PdfEvent $event)
{
	$templateName = $event->getTemplateName();
	$object = $event->getObject();
	if(is_a($object,'Thelia\Model\Order')){
		switch($templateName){
			case "invoice":
				$event->setFileName($object->getInvoiceRef());
			break;
			case "delivery":
				$event->setFileName($object->getDeliveryRef());
			break;
		}
	}
}