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

django_q/conf.py

@@ -63,6 +63,9 @@ class Conf:
     # ORM broker
     ORM = conf.get("orm", None)
 
+    # ORM support for read/write replicas
+    HAS_REPLICA = conf.get("has_replica", False)
+
     # Custom broker class
     BROKER_CLASS = conf.get("broker_class", None)