Add user attribute: active/inactive date

It would be nice it the system allowed for input activation/deactivation dates for users.

This is specially valuable in our case where a new user gets an assignment with relative deadlines (number of days to complete) but they will only access the system after a particular date. If we had an option to input that date as part of the activation/import process for this user, it would solve this problem.

Same for user deactivation. If a particular user license should be deactivated at a specific date, as an admin I would like to specify that date in advance in the users file rather than manually deactivate the user on that particular date.