Allow Bluetooth radio to be toggled in Airplane mode.

Add "bluetooth" to the list of toggleable radios. Because this string
is in the Settings DB, I had to bump the version number. Why is this in
the settings DB anyway, rather than a carrier config option?

I also discovered that the SystemUI package copied the entire contents of
res/values/defaults.xml from SettingsProvider, when I originally tried
to update the unreferenced SystemUI version of the setting. To prevent
future confusion, I removed all of the values from the SystemUI version
of res/values/defaults.xml.

Change-Id: Ib8a75c85b9db5c1963b65538ee2765d5087e67d2