Add support for custom user filtering.

django_etebase/utils.py

@@ -0,0 +1,12 @@
+from django.contrib.auth import get_user_model
+from . import app_settings
+
+
+User = get_user_model()
+
+
+def get_user_queryset(queryset, view):
+    custom_func = app_settings.GET_USER_QUERYSET
+    if custom_func is not None:
+        return custom_func(queryset, view)
+    return queryset