[FS#123] Root passwordless logins allowed even if there is an SSH public key, and user is not warned of this

[LEDE Bugs]

Ted Hess has taken ownership of the following task:

FS#123 - Root passwordless logins allowed even if there is an SSH public key, and user is not warned of this

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=123