White or black list processes in dispatcher

This is q&d solution just for testing.

resolwe/flow/managers/dispatcher.py

@@ -669,6 +669,17 @@ def process_data_object(data: Data):
 
         try:
             queryset = Data.objects.filter(status=Data.STATUS_RESOLVING)
+
+            whitelist = json.loads(os.environ.get("RESOLWE_PROCESS_WHITELIST", "null"))
+            blacklist = json.loads(os.environ.get("RESOLWE_PROCESS_BLACKLIST", "null"))
+
+            if whitelist:
+                assert isinstance(whitelist, list)
+                queryset = queryset.filter(process__slug__in=whitelist)
+            if blacklist:
+                assert isinstance(blacklist, list)
+                queryset = queryset.exclude(process__slug__in=blacklist)
+
             if data_id is not None:
                 # Scan only given data object and its children.
                 queryset = queryset.filter(