`Events.addAction()` does nothing

`addFilter` works, but it's action counterpart is just an empty function.

In the meantime, it looks like action callbacks can be triggered like this:

```js
jQuery( document ).on( 'ready.o2', function() {
// whatever you want here
} );
```

Start by reading Events.addAction() and comparing it with addFilter(), then inspect how the jQuery document event 'ready.o2' is used for action callbacks. Done means addAction() no longer silently does nothing and registered action callbacks can be triggered as intended.

Written by the indexing model from the issue text.