public async Task<IHttpActionResult> ChangePassword(ChangePasswordBindingModel model)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            IdentityResult result = await this.AppUserManager.ChangePasswordAsync(User.Identity.GetUserId(), model.OldPassword, model.NewPassword);

            if (!result.Succeeded)
            {
                return GetErrorResult(result);
            }

            return Ok();
        }
        public async Task<IHttpActionResult> ChangePassword(ChangePasswordBindingModel model)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            IdentityResult result = await this.AppUserManager.ChangePasswordAsync(User.Identity.GetUserId(), model.OldPassword, model.NewPassword);

            if (!result.Succeeded)
            {
                return GetErrorResult(result);
            }

            // sent user a mail notificatin about successfully password change
            await this.AppUserManager.SendEmailAsync(User.Identity.GetUserId(), "Change password confirmation", "Your password hasbeen changed successfully");

            return Ok();
        }