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.
Ok, I know why it fails. It did fail when you pass an argument to it. But note that it is safe to do:
```
promise.then(function() {
  // assertions
}).then(done, done);
```
The reason is that the function containing assertions returns nothing, so we don't need to wrap the function in this case.