item groups now have order - start page is now item group 1 (configurable in globals)

front-api/db/migrate/20150420044444_create_item_in_groups.rb

@@ -0,0 +1,13 @@
+class CreateItemInGroups < ActiveRecord::Migration
+  def change
+    create_table :item_in_groups do |t|
+      t.integer :item_id
+      t.integer :item_group_id
+      t.integer :position
+
+      t.timestamps null: false
+    end
+
+    drop_table "item_item_groups"
+  end
+end