assignment.index page fixed(modify dropbox). and assignment.show page fixed(from -> start, to -> end)
change @current_subjects and @outdate_subject in course.show view to match and condition.
add bundle gem modernizr, jquery-ui-rails.
add option model.
add compile_command column to problems table.
add compile_command field and field_for -> f.field_for in subject.new view, and add @problem.**s.build tosubjects controller.
add truncate on notice in courses.show page.
fixed fields_for problem, and add helper file_multiple_supported?, fixed problem.new page.
improve subject.show page.
add modernizr custom build, and fixed modernizr test to woking datepicker.
refactoring all controllers.
add presence validate to all models.
add time_localize_date, simple format and truncate function to views.