Notifications: Don't load if not loaded

[dd32]

I don't really know why this happens, but ready.o2 fires after preload.o2, but the ready.o2 hook is fired before the preload.o2 hook has run too.

I assume this is because o2 is assuming that ready.o2 is unique to o2, but actually it's just a namespaced variant of ready, so document ready triggers it, and then o2 triggers it.

15:20:23.374 notifications.js?ver=6.5-beta2-57697:81 ready.o2 without notifs
15:20:23.403 notifications.js?ver=6.5-beta2-57697:76 preload.o2
15:20:23.432 notifications.js?ver=6.5-beta2-57697:81 ready.o2 with notifs

Fixes #225