updating routes to disallow deletion of used exams.

Signed-off-by: Gnanakeethan Balasubramaniam <gnanakeethan@gmail.com>
correcting mistake.

Signed-off-by: Gnanakeethan Balasubramaniam <gnanakeethan@gmail.com>
adding clear cache option to administrator.

Signed-off-by: Gnanakeethan Balasubramaniam <gnanakeethan@gmail.com>