This also allows WiFi passwords to be remembered. The underlying
tool (connman) allows to store passswords (that's why it auto connects
whenever you boot a Lakka device), so we expose this so that the user
does not have to re-input the pass when connecting to a saved wifi.
Option to forget a password to come in a future PR, for now a password
is automatically forgotten if the Wifi connect operation fails (we assume
it fails due to password).
Changes the WiFi API to enable these features of course!
