Windows: Don't store password in keyring in portable mode

Otherwise its not really portable if it stores data in the system keyring

gajim/common/config.py

@@ -689,6 +689,9 @@ def _init_options(self):
         for opt in self.__options[0]:
             self.__options[1][opt] = self.__options[0][opt][Option.VAL]
 
+        if gajim.IS_PORTABLE:
+            self.__options[1]['use_keyring'] = False
+
     def _really_save(self):
         from gajim.common import app
         if app.interface: