Fix some bugs.
Fix some bugs.

Remove add the update_timestamp and node_timestamp in _preValidate function
to pass spec validation and remove them in postValidation so that they done
get added to the document.

jimklo/LearningRegistry,jimklo/LearningRegistry,LearningRegistry/LearningRegistry,LearningRegistry/LearningRegistry,LearningRegistry/LearningRegistry,LearningRegistry/LearningRegistry,jimklo/LearningRegistry,jimklo/LearningRegistry,jimklo/LearningRegistry,jimklo/LearningRegistry,jimklo/LearningRegistry,jimklo/LearningRegistry,LearningRegistry/LearningRegistry,LearningRegistry/LearningRegistry,jimklo/LearningRegistry,LearningRegistry/LearningRegistry