Avoiding fails at session_restore

Before when session restore fails the webui was answering "Unknown status 200" as content.
Now it produce 2 log messages (maybe)

lodel/auth/client.py

         if cls._instance.__session_token is not None:
             raise ClientAuthenticationError("Trying to restore a session, but \
 a session is allready started !!!")
-        cls._instance.__datas = SessionHandler.restore(token)
-        cls._instance.__session_token = token
+        try:
+            cls._instance.__datas = SessionHandler.restore(token)
+            cls._instance.__session_token = token
+        except ClientAuthenticationFailure:
+            logger.warning("Session restoring fails")
         return copy.copy(cls._instance.datas)
     
     ##@brief Return the current session token or None

plugins/webui/run.py

         #to log messages with client infos
         client = WebUiClient(env['REMOTE_ADDR'], env['HTTP_USER_AGENT'], None)
         session_token = load_cookie(request)
-        if session_token is not None:
+        if session_token is not None and len(session_token) > 0:
             WebUiClient.restore_session(session_token)
-            #next line is for testing purpose
-            print("ACCESS DATAS : ", WebUiClient['last_request'])
         session_token = None
-        #next line is for testing purpose
-        WebUiClient['last_request'] = time.time()
         
         try:
             controller = get_controller(request)