Fix non-existant mode attribute in hidden networks

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Fix hidden networks profile loading

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Fix hidden network params loading and saving

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>