CRM-15714 CiviContribute convert validateCreditCard to validatePaymentIn...

...strument

The validateCreditCard function is too restrictive for both SWIPE and DirectDebit payment processors. Convert those calls to a new validatePaymentInstrument that only invokes validateCreditCard for credit card payment processors, and also allows SWIPE processors to override it.
@adixon can you please change this line to $payment->validatePaymentInstrument($values, $errors);