crashes on gnome keyring delete server without password

[pawciobiel]

From the main dialog, after adding a server without a password, when trying to remove it, app throws

Traceback (most recent call last):
  File "./gtkvncviewer.py", line 314, in add_server
    gconf.client_get_default().set_int(GCONF_AUTH_KEY, auth_token)
UnboundLocalError: local variable 'auth_token' referenced before assignment

and

Traceback (most recent call last):
  File "./gtkvncviewer.py", line 235, in delete_clicked
    auth_token = entry.get_value().get_int()
AttributeError: 'NoneType' object has no attribute 'get_int'