CRM-13475 - Tweak to error message text.

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* CRM-13475: Entering an invalid credit card number gives the wrong field validation error
  http://issues.civicrm.org/jira/browse/CRM-13475

CRM/Core/Payment/Form.php

@@ -262,7 +262,7 @@ class CRM_Core_Payment_Form {
       );
 
       $form->addRule('credit_card_exp_date',
-        ts('Credit card expiration date cannot be a past date.'),
+        ts('Card expiration date cannot be a past date.'),
         'currentDate', TRUE
       );
 
@@ -355,16 +355,16 @@ class CRM_Core_Payment_Form {
       if (!empty($values['credit_card_number']) &&
         !CRM_Utils_Rule::creditCardNumber($values['credit_card_number'], $values['credit_card_type'])
       ) {
-        $errors['credit_card_number'] = ts('Please enter a valid Credit Card Number');
+        $errors['credit_card_number'] = ts('Please enter a valid Card Number');
       }
       if (!empty($values['cvv2']) &&
         !CRM_Utils_Rule::cvv($values['cvv2'], $values['credit_card_type'])
       ) {
-        $errors['cvv2'] = ts('Please enter a valid Credit Card Verification Number');
+        $errors['cvv2'] = ts('Please enter a valid Card Verification Number');
       }
     }
     elseif (!empty($values['credit_card_number'])) {
-      $errors['credit_card_number'] = ts('Please enter a valid Credit Card Number and Type');
+      $errors['credit_card_number'] = ts('Please enter a valid Card Number');
     }
   }