Support relative redirects in grid (#2805)

Author: Jason Watt

java/server/src/org/openqa/grid/internal/TestSession.java

@@ -488,7 +488,7 @@ private void processResponseHeaders(HttpServletRequest request, HttpServletRespo
       // the location needs to point to the hub that will proxy
       // everything.
       if (name.equalsIgnoreCase("Location")) {
-        URL returnedLocation = new URL(value);
+        URL returnedLocation = new URL(remoteURL, value);
         String driverPath = remoteURL.getPath();
         String wrongPath = returnedLocation.getPath();
         String correctPath = wrongPath.replace(driverPath, "");