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.
I'm not sure about this. I think maybe this could be avoided by resolving the promise **then** returning it in mock_lazy_loader.js
I'd appreciate any pointers..