Changed the Student Flashcard dashlet and added the Attendance Report dashlet (% of teachers reporting).

Changed the Student Flashcard dashlet and added the Attendance Report dashlet (% of teachers reporting).

Added comments to show what I was doing, especially if it was something that I thought I may want to rewrite. The AttendanceSubmissionPercentageDashlet in ecwsp/attendance/dashboards.py has an awful case of not adhering to DRY, but I couldn't think of how to avoid it at the time. Everything else adheres to good practices.