Cleanup set-password dialog

Cleanup set-password dialog

* hildon-widgets/hildon-set-password-dialog.[ch]
        (hildon_set_password_dialog_set_domain): gchar * param is const
        (hildon_set_password_dialog_new_with_default): likewise.

        * hildon-widgets/hildon-set-password-dialog.c

        (hildon_set_password_set_property): setting 'modify-protection'
        now creates the UI

        (hildon_set_password_get_property): fixed broken 'domain' (missing
        break statement!) and 'modify-protection' (was a null operation)
        properties; code simplified.

        (hildon_set_password_dialog_constructor),
        (create_contents),
        (hildon_set_password_dialog_class_init),
        (hildon_set_password_dialog_init):
        hildon_set_password_dialog_constructor removed as weird and
        obsolete and replaced with new function create_contents; fixed
        leaking group variable; removed some unused, outdated code that
        was already commented out.

        (hildon_set_password_response_change),
        (hildon_set_password_response_set): GtkWindow *parent arguments
        changed to gpointer unused; cleaned up unnecessary strcmp's

        (hildon_checkbox_toggled): fixed typo in function name (checbox ->
        checkbox). gpointer renamed to be more descriptive; Code simplified

        (hildon_set_password_dialog_get_type): empty function argument
        list replaced with void keyword.

        (hildon_set_password_dialog_new),
        (hildon_set_password_dialow_new_with_default): simplified by
        having the simpler constructor call the more complex one, not vice
        versa; moved callback connects to create_contents since they
        depend on the status of 'modify-protection' property

        (hildon_set_password_dialog_get_password): type check added
        (hildon_set_password_dialog_get_protected): likewise
        (hildon_set_password_dialog_set_domain): likewise