Fix Bluetooth Settings activity memory leak.

There were two leaks in Bluetooth Settings: one when rotating the
    phone and other when scanning for bluetooth devices.

src/com/android/settings/bluetooth/BluetoothSettings.java

@@ -188,7 +188,8 @@ public class BluetoothSettings extends PreferenceActivity
         super.onPause();
 
         mLocalManager.setForegroundActivity(null);
-
+        mDevicePreferenceMap.clear();
+        mDeviceList.removeAll();
         unregisterReceiver(mReceiver);
 
         mLocalManager.unregisterCallback(this);