Initialize ritz with default authenticated value

Default value is None

src/zinolib/ritz.py

@@ -351,6 +351,7 @@ def __init__(self, server, port=8001, timeout=10, username=None, password=None):
 
         self._sock = None
         self.connStatus = False
+        self.authenticated = None
         self.server = server
         self.port = port
         self.timeout = timeout