Preloading in ApplicationRoute#activate doesn't make sense

`model` hooks for all routes run before any of the `activate` hooks.

Consequently this preload code only runs after all of the required models are fetched which more or less defeats the purpose of preloading.

I don't know if it is a good idea to recommend preloading in the `model` hook or somewhere else. If anyone wants to suggest a different place I can update.