Fixed bug in WirelessSettings where it was asking users for a PIN when
they weren't restricted. Did this by refactoring the preference level
pin checking into the superclass, where it checks for the restricted mode first.
Also pin protected changes to certificates for restricted users.
Change-Id: I8310fd39f0862159668318fc1360ec6859cc00d5
When these screens are locked down with user restrictions,
it should prompt the user for the restrictions pin before allowing
access to the settings screen.
Change-Id: Iadbb087da2d9470b855ea0bea89f2da1ffb9e854
Creates an easy way to ask for the restriction pin before
allowing access to a settings page. Does this to the WiFiSettings.
Change-Id: I49734f66e09b6449596412ecf6fc1113bf57ce7f