Add "change" as KeyboardEvent

Like:

```
    createEvent: function(type, options) {
        if (/^mouse(over|out|down|up|move)|(dbl)?click$/.test(type)) {
            return this.mouseEvent(type, options);
        } else if (/^key(up|down|press)|change$/.test(type)) {
            return this.keyboardEvent(type, options);
        }
    },
```

It'll support: `object.simulate("change")`.
