OwinOAuthProviders Linkedin fix

gistfile1.cs

// Request the token
                HttpResponseMessage tokenResponse =
                    await httpClient.GetAsync(string.Format("{0}?grant_type=authorization_code&code={1}&redirect_uri={2}&client_id={3}&client_secret={4}",
                        TokenEndpoint, code, redirectUri, Options.ClientId, Options.ClientSecret));