Peer Assessment Interface by Axel added

...c/main/java/unipotsdam/gf/interfaces/IPeerAssessment.java

...ipotsdam/gf/modules/assessment/controller/Assessment.java

...tsdam/gf/modules/assessment/controller/AssessmentDAO.java

...tsdam/gf/modules/assessment/controller/FBAssessement.java

...potsdam/gf/modules/assessment/controller/Performance.java

...m/gf/modules/assessment/controller/StudentIdentifier.java

...ipotsdam/gf/modules/munchkin/controller/MunchkinImpl.java

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

gemeinsamforschen/web/WEB-INF/web.xml

gemeinsamforschen/web/index.jsp