Feature/improves multiple databases support (#561)

* feat: adds docker local files to ignore

* feat: adds replica key to django q settings

* feat: adds multiple database routers testing utility

* feat: ensures scheduler works with multiple databases and replicas

* feat: adds docker image to support containerized development

* refactor: removes unnecessary import

* style: improves import styling

* docs: adds replica setting to configure documentation

docs/configure.rst

@@ -339,6 +339,16 @@ Using the Django ORM backend will also enable the Queued Tasks table in the Admi
 If you need better performance , you should consider using a different database backend than the main project.
 Set ``orm`` to the name of that database connection and make sure you run migrations on it using the ``--database`` option.
 
+When using the Django database as a message broker, you can set the ``has_replica`` boolean keyword to ensure Django-Q works properly letting a `Database Router <https://docs.djangoproject.com/en/3.2/topics/db/multi-db/>`__. ::
+
+    # example ORM broker connection with replica database
+
+    Q_CLUSTER = {
+            ...
+            'orm': 'default',
+            'has_replica': True
+        }
+
 .. _mongo_configuration:
 
 mongo