- Mark more strings for further translations
- in verbose names
- in the __str__ method
- Turn all verbose names into lowercase
- Add more verbose names
- Set an ordering on gestion.EventCommentField
- More database constraints on EventCommentValue
- `TextField` is not nullable
(https://docs.djangoproject.com/en/1.11/ref/models/fields/#null)
- `unique_together` constraint on the two fk
