Implemented a smart diff algorithm on the server side to detect actual UPDATES.
Each entity is serialized to a jsonObject, and their before and after states
are compared. Added tests that exercise this smart diff-ing.

Patch by: amitmanjhi
Review by: rjrjr (desk review)


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8570 8db76d5a-ed1c-0410-87a9-c151d255dfc7