Add method payment_method to get the payment method from a payment

- Method `payment_method_name` now use `payment_method`

app/helpers/spree/payment_methods_helper.rb

@@ -1,9 +1,13 @@
 module Spree
   module PaymentMethodsHelper
-    def payment_method_name(payment)
+    def payment_method(payment)
       # hack to allow us to retrieve the name of a "deleted" payment method
       id = payment.payment_method_id
-      Spree::PaymentMethod.find_with_destroyed(id).name
+      Spree::PaymentMethod.find_with_destroyed(id)
+    end
+
+    def payment_method_name(payment)
+      payment_method(payment).name
     end
   end
 end