Gradebook update warning notification uses notifysuccess

The code for showing warnings when gradebook things change use a notifysucess state, which seems inappropriate.

https://github.com/moodle/moodle/blob/v2.8.6/grade/lib.php#L489-L534

All the PHP code uses "warning" in it's variable names, and the text clearly sounds like something that's not a success, but a warning.

Presumably this is because, since Moodle's front-end generally doesn't have an intermediate "warning" status, comparable to Bootstrap's alert-warning, the developer had the choice of notifyerror and notifysuccess thought that error was too strong in this case.

Maybe it's time to add an intermediate level of notification?