Added group attribute to each GHOPProgram property so it is grouped on edit/create forms. Added 3 new groups, "Contest Rules" group, "Prize Information" group and "Task Settings" group to organize the properties in a useful manner on the edit/create forms. Reviewed by: Lennard de Rijk

Changed GHOP module imports to be consistent with rest of Melange code. The imports used the from <module-path> import <module> as <local_module_name> syntax. These kinds of imports are changed to import <module_path.module_name> syntax to be consistent with the Melange code base. Reviewed by: Lennard de Rijk

Changed the property that holds the minimum age required for Students to participate in a GHOP based program. Added a new property student_min_age_as_of to hold the DateTime from when the minimum age should be reached. Changed student_min_age property to now store the student minimum age as an integer. This all feel more user friendly then letting the program admin calculate the required DateTime. Storing the two properties is then still needed in this case since information might be lost otherwise when the program admin brings up the edit view. Reviewed by: Lennard de Rijk