Basic events operations.

1. List
2. Create
3. Update
4. Destroy

Operation 1 requires membership.
Operation 2, 3, 4 requires vice president privilege or above.
Fix the issue of erroneously deleted i18n files of department controller.
Attendence feature.

Take, accept, reject and delete attendences.
All-attend feature.

One-click function to make all members take attendence of an event.
zh localization for event and attendence features.
Add memo column in events indexing page.
Add associate dependency to prevent orphaned records.