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.
Benjamin Niemann <pink at odahoda dot de>: Main developer of Python target.
Clinton Roy <clinton.roy at gmail dot com>: AST templates and runtime.