Added methods to GradingRecord Logic to facilitate creating/updating them. UpdateOrCreateRecordsFor will batch put GradingRecords for a given SurveyGroup and StudentProject. getFieldsForGradingRecord will return the fields that need to be set for a single GradingRecord entity given a StudentProject, GradingSurveyGroup and if it is an update a GradingRecord entity.

""" models.py (even empty) currently required by the runtests.py to enable unit tests """