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

lib/tasks/items.rake

@@ -3,7 +3,7 @@
 namespace :items do
   task :tree_changes => :environment do
   	Item.all.each do |item|
-  		item.position -= 1
+  		item.position -= item.position > 5 ? 2 : 1
   		item.parent_ids = ancestors(item)
   		item.rename(:full_name, :path)
   		item.save