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 the assertion fails before this line, `done` is never called and you will get a timeout error. Please do:
```
).then(done, done);
```
We pass `done` as the second argument to make the test end correctly. It is not required to call `this.fail()` as mocha always checks the assertion.