Minor change: when the shifts capacity is locked, so that students can
not enroll, the teacher should be able to define groups for it, so that
it can be open only for them
Bug fix: checking if degree is selected
Bug fix: can not invoke super because it will give a cast error,
implementing own logic
Minor change: if the student already has chosen the same affinityCycle,
simply return that registration, instead of an error with no information
Bug Fix: Fixed expression for testing null user.
Bug Fix: overloading methods confuses the renderes and may result in class cast exceptions every once and a while.
Added service to 'dump' enrolment statistics for specified semesters.
Bumped version for release of 3.11.4
Merge branch 'release/3.11.4' into develop
Bumped version for development after release.
Bug fix: preventing NPE