namespaced model hooks

[ralfonso]

I shoehorned model hooks into the Java resources system, so it's currently convention over configuration and the functions in the hook files are not namespaced, which can introduce some nasty collision issues.

We need to think about how we can do namespaced hooks at the parent level. Hooks will need to work for all three components of a caribou site, so they can't live in the site/api/admin dirs.