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/DockEventReceiver.java

@@ -16,8 +16,6 @@
 
 package com.android.settings.bluetooth;
 
-import com.android.settings.bluetooth.LocalBluetoothProfileManager.Profile;
-
 import android.app.Service;
 import android.bluetooth.BluetoothA2dp;
 import android.bluetooth.BluetoothAdapter;
@@ -27,7 +25,6 @@ import android.bluetooth.BluetoothProfile;
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
-import android.content.IntentFilter;
 import android.os.PowerManager;
 import android.util.Log;