Shopify/active_merchant — pull request #365 by jduff (2012-05-22 14:15:48+00:00)
Title: SecurePayAu: fix credit card check

- Some ActiveMerchant users have their own credit card object that they
pass to ActiveMerchant so we shouldn't be checking for
ActiveMerchant::Billing::CreditCard explicitly but check that it looks
like a credit card instead (having a number method is a good check).

@Soleone @ntalbott for review