beaut: exchanged one list by one Map

.../src/main/java/unipotsdam/gf/config/GFDatabaseConfig.java

...m/gf/modules/assessment/controller/model/Performance.java

...essment/controller/service/AssessmentDBCommunication.java

...modules/assessment/controller/service/PeerAssessment.java

...es/assessment/controller/service/PeerAssessmentDummy.java

...tsdam/gf/modules/assessment/controller/view/QuizView.java

...orschen/src/main/webapp/assets/js/assessmentCalculator.js

...a/unipotsdam/gf/modules/assessment/TestAddAssessment.java

...ava/unipotsdam/gf/modules/peerassessment/HashMapTest.java