Add passing of given query string on history rewind
When starting the flow or requesting the first step with a query string, it got lost. (E.g. /flow/firstStep?foo=bar redirected to /flow/firstStep without the query string). The losing of the query string was caused by a redirect without any parameters. Now added canaling of the query string into the redirect, e.g. /flow?foo=bar redirects to /flow/firstStep?foo=bar as well as /flow/firstStep?foo=bar to /flow/firstStep?foo=bar.