config: Add method to sanitize string values from ini file.

rhodecode/config/middleware.py

@@ -431,3 +431,7 b' def _list_setting(settings, name, defaul'
         raw_value = raw_value.replace(',', ' ')
 
     settings[name] = aslist(raw_value)
+
+
+def _string_setting(settings, name, default):
+    settings[name] = settings.get(name, default).lower()