we have to put the new elements into IndividualCandidacySeriesGradeSet when we add elements in the SelectedDegreesSet
Merge pull request #572 from cbartol/ticket/rt#421640

Fixed the error of removing a degree from the selected degrees
The problem is not when the degree is removed from the list. The problem is when we edit the selected degrees and add a new element, this new element is not added to the IndividualCandidacySeriesGradeSet. Thus when removing something that does not exist it throws an exception.