Generate report cards

The system should be able to generate report cards in scheduled days or manually.
This feature should be done this way:
1. The scheduling will be handled by Cron, in order to allow the daemon to do other tasks much more faster.
2. The system should remind the teachers to add their comments and personal evaluation at least 4 weeks before the scheduled days.
3. There should be a subsystem which gets a JSON string from the main system and generates PDF files in order to print the grades or sends an email.