Check for credit card type and number on submit

I have been developing a direct payment method where payments are collected on third-party sites, hence I don't need to set the payment types for the form, the user doesn't need to give the credit card details at all.

According to the current behaviour _webform_submit_pay() tries to mask the credit card number even when it wasn't given by the user. This is causing theme_webform_display_pay() to fail, because the cc_number is set to **** **** ****, but I didn't implemented payment_types() because - like I said - it is a direct method.

function theme_webform_display_pay($element) {
  if ($element['#value']['cc_number']) {
    $value = $element['#value'];
    $pay_method = pay_method_load($element['#pmid']);
    $payment_types = $pay_method->payment_types();
    ...

We should check on submit if the credit card type and number is set, before doing anything with it.