Added failed_evaluations property to StudentProject model. This is used to store GradingRecords which state a fail for this project. It's a list because manual changes in GradingRecords might force multiple GradingRecords to state a fail. Also it needs to be clear which GradingRecords have been processed and with which grade_decision.

release: "1.2.3"
timestamp: 1243913623
api_versions: ['1']