Change soundFinished event parameters

@AmbientOSX In conjunction with virtual-world-framework/mars-game#190
When I checked it, `soundName` was going through as `undefined`, but I think that it has to be `soundDatum.soundDefinition.soundName`. I can change it back, and have the parameters be the instanceHandle object with another parameter. All I need is the `soundGroup` to check for VO, but do you think it would be better to pass more than that ( i.e. the entire definition) since the event is broader than just VO?