Use Spree::Address::Name to handle credit card names

The logic for splitting a name and concatenating name components should
be centralized in a single class.

core/app/models/spree/credit_card.rb

@@ -163,7 +163,7 @@ def has_payment_profile?
     #   the object to ActiveMerchant.
     # @return [String] the first name on this credit card
     def first_name
-      name.to_s.split(/[[:space:]]/, 2)[0]
+      Spree::Address::Name.new(name).first_name
     end
 
     # @note ActiveMerchant needs first_name/last_name because we pass it a
@@ -172,7 +172,7 @@ def first_name
     #   the object to ActiveMerchant.
     # @return [String] the last name on this credit card
     def last_name
-      name.to_s.split(/[[:space:]]/, 2)[1]
+      Spree::Address::Name.new(name).last_name
     end
 
     # @return [ActiveMerchant::Billing::CreditCard] an ActiveMerchant credit