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

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

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

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

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

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

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

            IdentityResult result = await this.UserManager.CreateAsync(user, model.Password);

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

            return this.Ok("Registration successful");
        }