Use CONFIG rather constants

Author: glensc

plexapi/myplex.py

@@ -571,7 +571,7 @@ def syncItems(self, client=None, clientId=None):
         if client:
             clientId = client.clientIdentifier
         elif clientId is None:
-            clientId = X_PLEX_IDENTIFIER
+            clientId = CONFIG.get('header.identifier')
 
         data = self.query(SyncList.key.format(clientId=clientId))