Fix bugs for shift_to and change items.rake for the missing position in db

app/controllers/admin/items_controller.rb

@@ -17,6 +17,8 @@ class Admin::ItemsController < ApplicationController
   end
 
   def update_position
+    item = Item.find(params[:id])
+    item.shift_to(params[:parent_id], params[:position])
     render :nothing => true
   end