add stub for local_id_for

Change-Id: I6d462ffb86a20ed197795c96437b5e281ae8fedf
Reviewed-on: https://gerrit.instructure.com/31793
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>

lib/stubs/shard.rb

@@ -1,5 +1,5 @@
 #
-# Copyright (C) 2011 Instructure, Inc.
+# Copyright (C) 2012 - 2014 Instructure, Inc.
 #
 # This file is part of Canvas.
 #
@@ -79,6 +79,10 @@ class Shard
     "default"
   end
 
+  def self.local_id_for(any_id)
+    [any_id, Shard.default]
+  end
+
   def self.global_id_for(any_id)
     any_id.is_a?(ActiveRecord::Base) ? any_id.global_id : any_id
   end