django-tenants added, and configurated customers app

core/apps/customers/apps.py

@@ -0,0 +1,10 @@
+from django.apps import AppConfig
+
+
+class CustomersConfig(AppConfig):
+    default_auto_field = 'django.db.models.BigAutoField'
+    name = 'core.apps.customers'
+
+    def ready(self):
+        import core.apps.customers.admin
+