Configurable should watch all config files

We now use the global ImportManager for watching config files,
because the configured class may not be the Application itself,
but also something which does not have an _imp attribute.

Author: Cito

webware/MiscUtils/Configurable.py

@@ -141,9 +141,12 @@ def userConfig(self):
         if contents.lstrip().startswith('{'):
             raise ConfigurationError(
                 'Configuration via a dict literal is not supported anymore.')
-        imp = getattr(self, '_imp', None)
-        if imp:
-            imp.watchFile(filename)
+        try:
+            from ImportManager import ImportManager
+            ImportManager().watchFile(filename)
+        except Exception as e:
+            print('WARNING: Config file', filename, 'cannot be watched:', e)
+            print()
         config = self.configReplacementValues().copy()
         try:
             exec(contents, config)