proper i18n of last ordergroup order (thanks @JuliusR)

app/models/ordergroup.rb

@@ -26,6 +26,11 @@ class Ordergroup < Group
     User.natural_order.all.reject { |u| (users.include?(u) || u.ordergroup) }
   end
 
+  # the most recent order this ordergroup was participating in
+  def last_order
+    orders.order('orders.starts DESC').first
+  end
+
   def value_of_open_orders(exclude = nil)
     group_orders.in_open_orders.reject{|go| go == exclude}.collect(&:price).sum
   end