add hyper-loaded-defined classes

In the past there was no way to tell if the app was loading or had loaded but the value was undefined. This branch introduces two classes for that:

* `ng-hyper-loaded-defined`
* `ng-hyper-loaded-undefined`

The following conditions will now exist in the lifecycle of a binding:

* `ng-hyper-loading` // ng-hyper is traversing the API and has not returned a value
* `ng-hyper-loaded ng-hyper-loaded-defined` // the API has returned a defined value for the given path
* `ng-hyper-loaded ng-hyper-loaded-undefined` // the API has returned an undefined value for the given path

This feature should make it easier to do loading states that are only present during the initial state.