fixup for 6bff9d1

Modify `_it.shouldBeDenied` to get the expected status code from
`this.aclErrorStatus` instead of a function parameter.

Intended usage:

```js
describe('/users', function() {
  beforeEach(function() {
    this.aclErrorStatus = app.models.User.settings.aclErrorStatus;
  });

  lt.it.shouldBeDeniedWhenCalledAnonymously('GET', urlForUser);
  lt.it.shouldBeDeniedWhenCalledUnauthenticated('GET', urlForUser);
  //...
});
```