public function postRegister(RegisterRequest $request)
 {
     $append = ['password' => bcrypt($request->get('password')), 'friends' => '{}'];
     if ($user = User::create(array_merge($request->except(['_token', 'confPassword', 'password']), $append))) {
         $user->role()->attach($user->id, ['role_id' => 3]);
         return $request->ajax() ? json_encode(['error' => 0, 'forceLogin' => 1, 'message' => 'Create account success. Please login now!']) : redirect()->route('login')->with(['message' => 'Create account success. Please login now!']);
     }
     return $request->ajax() ? json_encode(['error' => 1, 'message' => 'unexpected error!']) : redirect()->route('register')->withErrors('Unexpected error!');
 }