Enables network blocking for specific classrooms:
- Each block has its own file.
- Blocks applies for 2h only when the file exists (naming as
classroom-weekday-start). - This is the list of valid blocks:
- ada-mon-19
- ada-tue-19
- ada-wed-16
- torvalds-wed-19
- torvalds-thu-19
- torvalds-fri-16