Duplicated config options run_on_login and scriptlogin/script

[jfrsw]

While trying to implement a new stop_user_shell option for issue #39, I have found out that after commit e9727d2 there seems to be two settings for running scripts on user login: the old run_on_login on section [node] and the new script on section [scriptlogin]. Both options are also implemented on different places on the source code (run_on_login on LoginWindow::attemptLoginSuccess and scriptlogin/script on NetworkClient::doLoginTasks).

If those options are really duplicated, I think it would be good to chose either one (scriptlogin/script would be equivalent to run_on_login, and scriptlogout/scriptcould be implement as a new run_on_logout), and to decide which place works best for implementing this kind of option (LoginWindow::attemptLoginSuccess or NetworkClient::doLoginTasks).