Added new constructors to GradeRange and GradingScheme classes. Used these in AddGradingScheme controller.
minor changes to grading scheme gui
Changed fxml file for AddClass to match the new model data (with year)
added check for empty year to avoid exceptions. sets default year to 0 if none entered.
Merge branch 'master' of https://github.com/jjfazio/308Grader