Allow update any login name from admin account

[camlafit]

An admin can't change login name. Only user can change its username.

Should be nice to allow this change, maybe with an option server. When api is used, admin must be more flexibility to mange account.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs during the next 2 weeks. Thank you for your contributions.