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.
An extra indention is not required. We could do either
```
xxx().then(function(data) {
  // ...
});
```
or
```
xxx()
.then(function() {
  // ...
});
```
I would prefer the first one if it does not exceed the character limit.