public static function addPaymentInfo()
 {
     RecruiterController::requireLogin();
     global $params;
     $recruiterId = $_SESSION['_id'];
     $customerId = RecruiterModel::getCustomerId($recruiterId);
     if (is_null($customerId)) {
         // Create new customer id.
         $email = $_SESSION['email'];
         $customerId = StripeBilling::createCustomer($email);
         RecruiterModel::setCustomerId($recruiterId, $customerId);
     }
     // Add card info.
     $tokenObj = $params['token'];
     $token = $tokenObj['id'];
     $card = StripeBilling::addCard($customerId, $token);
     echo toJSON($card);
 }