Run submission in a separate thread, and more explicit state

Also more explicit timeouts and an overall better handling of errors.

benchmark/submission/auth.py

@@ -50,7 +50,7 @@ class TokenHTTPServer(http.server.HTTPServer):
         self.log.debug('Finding free port starting at %s', local_addr)
         return sockutil.find_free_port(local_addr)
 
-    def wait_for_token(self, timeout=None):
+    def wait_for_token(self, timeout: float):
         """Starts the HTTP server, waits for the Token."""
 
         if self.auth_token is None: