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.
If it fails it most likely won't be calling .reject() on the promise so a failure callback will never happen either.
Also we *know* the promise is resolved because we're stubbing getJSON