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

            ExternalLoginData externalLogin = ExternalLoginData.FromIdentity(User.Identity as ClaimsIdentity);

            if (externalLogin == null)
            {
                return InternalServerError();
            }

            ApplicationUser user = new ApplicationUser
            {
                UserName = model.UserName
            };
            user.Logins.Add(new IdentityUserLogin
            {
                LoginProvider = externalLogin.LoginProvider,
                ProviderKey = externalLogin.ProviderKey
            });

            IdentityResult result = await UserManager.CreateAsync(user);
            IHttpActionResult errorResult = GetErrorResult(result);

            if (errorResult != null)
            {
                return errorResult;
            }

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

            var info = await Authentication.GetExternalLoginInfoAsync();
            if (info == null)
            {
                return InternalServerError();
            }

            var user = new ApplicationUser() { UserName = model.Email, Email = model.Email };

            IdentityResult result = await UserManager.CreateAsync(user);
            if (!result.Succeeded)
            {
                return GetErrorResult(result);
            }

            result = await UserManager.AddLoginAsync(user.Id, info.Login);
            if (!result.Succeeded)
            {
                return GetErrorResult(result); 
            }
            return Ok();
        }