[Degree] Refactor: Creating a DegreeCurricularPlan for a Degree no longer depends on the degree being bologna.
Fix: CurricularCourse.getCode() should use the CompetenceCourse.getCode, when available.
Fix: Corrected a problem with the first year of the AcademicYearCE, which could not be used as a timestamp type in mysql (before 1970)