Fix request json serialization

It's not an issue right now, but when we start sending json over the
celry wire, it'll fatal as request object is a dictionary and doesn't
have format method

ores/scoring_systems/celery_queue.py

@@ -56,12 +56,12 @@ def _initialize_tasks(self):
         @self.application.task(throws=expected_errors,
                                queue=DEFAULT_CELERY_QUEUE)
         def _process_score_map(request, model_names, rev_id, root_cache):
-            logger.info("Generating a score map for {0}"
-                        .format(request.format(rev_id, model_names)))
-
             if not isinstance(request, ScoreRequest):
                 request = ScoreRequest.from_json(request)
 
+            logger.info("Generating a score map for {0}"
+                        .format(request.format(rev_id, model_names)))
+
             score_map = ScoringSystem._process_score_map(
                 self, request, rev_id, model_names,
                 root_cache=root_cache)
@@ -94,7 +94,7 @@ def _process_missing_scores(self, request, missing_model_set_revs,
                     continue
                 root_cache = {str(k): v for k, v in root_caches[rev_id].items()}
                 result = self._process_score_map.delay(
-                    request.to_json(), missing_models, rev_id, root_cache)
+                    request, missing_models, rev_id, root_cache)
                 self._lock_process(missing_models, rev_id, request,
                                    injection_cache, result.id)