Resolve "Invalid preference name returned by setting_name_from_field"

Closes #13 (closed)

aleksis/apps/ldap/util/ldap_sync.py

@@ -29,7 +29,7 @@ TQDM_DEFAULTS = {
 
 def setting_name_from_field(model, field):
     """Generate a setting name from a model field."""
-    return "additional_field_%s_%s" % (model._meta.label, field.name)
+    return "additional_field_%s_%s" % (model._meta.label_lower.replace(".", "__"), field.name)
 
 
 def syncable_fields(model):