fix sql tables, fix db communication, pngs for wiki

...dback/peerfeedback/Controller/PeerFeedbackController.java

...peer2peerfeedback/peerfeedback/View/PeerFeedbackView.java

gemeinsamforschen/src/main/webapp/feedback/give-feedback.jsp

...mforschen/src/main/webapp/feedback/js/givepeerfeedback.js

...mforschen/src/main/webapp/feedback/js/viewpeerfeedback.js

gemeinsamforschen/src/main/webapp/libs/img/givefeedback.png

...mforschen/src/main/webapp/libs/img/projekt_uebersicht.png

...orschen/src/main/webapp/libs/img/studenten_uebersicht.png

...rschen/src/main/webapp/libs/img/viewfeedback_recieved.png

gemeinsamforschen/src/main/webapp/project-student.jsp

...en/src/scripts/dbschema/createDummyUsersGroupsProject.sql

gemeinsamforschen/src/scripts/dbschema/peerfeedback