Supplying testId and running the `restartTest` gives "Invalid URL, please try submitting your test request again." I think this is due to the API call (/runtest.php?resubmit=testId) is sent as a [GET request](https://github.com/WebPageTest/webpagetest-api/blob/master/lib/webpagetest.js#L541) while the server expects a [POST request](https://github.com/WPO-Foundation/webpagetest/blob/master/www/runtest.php#L139).