Introduced invoices and deliveries. Integration (especially of deliveries) isn't finished yet.

app/models/membership.rb

@@ -1,3 +1,13 @@
+# == Schema Information
+# Schema version: 20090102171850
+#
+# Table name: memberships
+#
+#  id       :integer(4)      not null, primary key
+#  group_id :integer(4)      default(0), not null
+#  user_id  :integer(4)      default(0), not null
+#
+
 class Membership < ActiveRecord::Base
   
   belongs_to :user