Vanguard client: Accept 500 errors on initial response

Though their server returns a 500 HTTP status code, it still sets the
required cookies on the response that we can use to make a second
request.

Author: aclindsa

basic_client.go

@@ -74,7 +74,7 @@ func (c *BasicClient) RawRequest(URL string, r io.Reader) (*http.Response, error
 	}
 
 	if response.StatusCode != 200 {
-		return nil, errors.New("OFXQuery request status: " + response.Status)
+		return response, errors.New("OFXQuery request status: " + response.Status)
 	}
 
 	return response, nil

vanguard_client.go

@@ -64,7 +64,7 @@ func (c *VanguardClient) RequestNoParse(r *Request) (*http.Response, error) {
 	// Fortunately, the initial response contains the cookie we need, so if we
 	// detect an empty response with cookies set that didn't have any errors,
 	// re-try the request while sending their cookies back to them.
-	if err == nil && response.ContentLength <= 0 && len(response.Cookies()) > 0 {
+	if response != nil && response.ContentLength <= 0 && len(response.Cookies()) > 0 {
 		b, err = r.Marshal()
 		if err != nil {
 			return nil, err