Translation correction
rename GradeAnswer to LikertAnswer
adding GradeAnswer and redefining total grade calculation
redefine migration, added missing settings
adapting test_data and completing translations
fixing vote_test
Merge pull request #349 from janno42/summary_grade

LikertAnswer/GradeAnswer
Merge branch 'master' of github.com:fsr-itse/EvaP into release