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.
Instead of just adapting this code to have the promise invoke the callback I'd refactor it to return a promise instead and change the related code. This is a matter of personal taste though and your choice is less risky obviously but think about it, the result would be cleaner and more compact.