/**
* Transmits the proper headers to cause a download to occur and to identify the file properly
* @return nothing
*/
function headers()
{
header("Content-Type: application/force-download");
header("Content-Type: application/octet-stream");
header("Content-Type: application/download");
header("Content-Disposition: attachment;filename=" . Excel::filename($this->title) . ".xls ");
header("Content-Transfer-Encoding: binary ");
}