public Task <IActionResult> ChangePassword(string userId, string oldPwd, string newPwd)
 {
     return(Task.Factory.StartNew <IActionResult>(() =>
     {
         var result = _userRepository.ChangePassword(userId, oldPwd, newPwd);
         return Json(new { success = result.Item1, msg = result.Item2 });
     }));
 }