Include activationData in viewModel.beforeActivate

I think it would be nice if we can include `activationData` as part of `viewModel.beforeActivate` parameter. In some other case I need to calculate received parameters and inject the result into my view model. In some reason I can't use `router.onNavigationComplete` to do that, so I must override `router.activeItem.settings.beforeActivate` method so it will looks like this:

```
router.activeItem.settings.beforeActivate = function (newItem, params) {
   newItem.userPath(params.user + '/' + params.group);
   return newItem;
};
```

I made sample app on https://github.com/budiadiono/DurandalMovieApp/tree/IntuitiveUserPath. On that sample app actually is fine to use `router.onNavigationComplete` but not for my other app that I've been developing right now. What do you think?