Json Toolkit 2.1 Update

The Json Toolkit has been updated to version 2.1 to fix a bug about deserializing data containing null values as reported by developers. The new library and the source code can be downloaded at CodePlex:  http://jsontoolkit.codeplex.com/ . Since Facebook Graph Toolkit does not use the deserialize feature at the moment, this fix does not affect applications that use FGT.