Enable reverse tethering in BT settings screen.

- Enable support for reverse tethering in BT settings.
- Add string resource for "Auto connect" preference.
- Remove unused imports and other minor cleanups.
- Add isConnectable() and isAutoConnectable() methods to Profile
  enum type and remove isConnectableProfile() method.

Change-Id: Ie606db04028a8278e98231f0671a388671f2f067

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

@@ -72,7 +72,7 @@ public class RequestPermissionActivity extends Activity implements
 
     private AlertDialog mDialog = null;
 
-    private BroadcastReceiver mReceiver = new BroadcastReceiver() {
+    private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
 
         @Override
         public void onReceive(Context context, Intent intent) {