Bug 1062798 - Replace custom JSON loaders with LazyLoader.getJSON in Settings App

Replaces custom JSON loaders with the LazyLoader.getJSON helper.
Replaced code in the app permissions, display, help, search and sound panels.
Also replaced within the APN utils module.
not the tidiest .. but using `then(done, done)` broke tests. I think it picked up args from the promise callback?
might be a cleaner way using `.bind()` but I can't think of it right now.