config: Add argument to convert settings to lowercase or not.

Most settings should be converted to lowercase during app init.
But at least file system paths should not lower cased. Threfore
we need a switch to control it.

rhodecode/config/middleware.py

@@ -473,5 +473,8 b' def _list_setting(settings, name, defaul'
         settings[name] = aslist(raw_value)
 
 
-def _string_setting(settings, name, default):
-    settings[name] = settings.get(name, default).lower()
+def _string_setting(settings, name, default, lower=True):
+    value = settings.get(name, default)
+    if lower:
+        value = value.lower()
+    settings[name] = value