public function sendReceipt(Cart $cart)
{
$mg = new Mailgun(self::API_KEY);
$domain = "mg.fullprintcamping.com";
$user = $cart->user()->first();
$response = $mg->sendMessage($domain, array('from' => '*****@*****.**', 'to' => $user->email, 'subject' => "Your order at FullPrintCamping.com", 'text' => "fullprintcamping.com/order-details/" . $cart->id));
var_dump($response);
}