Update registry.py

Made listener requiered.

lib/modules/persistence/userland/registry.py

@@ -39,7 +39,7 @@ class Module:
             },
             'Listener' : {
                 'Description'   :   'Listener to use.',
-                'Required'      :   False,
+                'Required'      :   True,
                 'Value'         :   ''
             },
             'KeyName' : {
@@ -233,4 +233,4 @@ class Module:
 
         script += "'Registry persistence established "+statusMsg+"'"
 
-        return script
+        return script