add config_file as a property to the Config class

deluge/config.py

@@ -295,6 +295,10 @@ class Config(object):
             log.error("Error moving new config file: %s", e)
             return
     
+    @property
+    def config_file(self):
+        return self.__config_file
+
     @prop
     def config():
         """The config dictionary"""