Modified AnswerKey builder to works the same as QuestionForm builder.
UpdateQualificationScore operation implemented.
Typo fixed.
GetQualificationScore operation implemented.
Small fix to avoid to qualifications get accumulated each time the
method is called.
added UpdateQualificationScore api
Add ending newlines
Merge in #41
Fix get qualification score, add tests
Bump to 2.12.0, closes #42, closes #41