Add AU Group Notifications plugin

plugins/au_group_notifications/LICENCE.txt

plugins/au_group_notifications/actions/set_notifications.php

plugins/au_group_notifications/adminform.php

plugins/au_group_notifications/languages/en.php

plugins/au_group_notifications/manifest.xml

plugins/au_group_notifications/start.php

...tifications/views/default/au_group_notifications/form.php

...ns/views/default/settings/au_group_notifications/edit.php