Added $promise & $resolved properties

[ngResource.$resource](http://docs.angularjs.org/api/ngResource.$resource) defines a `$promise` property and a `$resolve` property on the Resource. They are currently missing from the definition.

> Class actions return empty instance (with additional properties below). Instance actions return promise of the action.
>
> The Resource instances and collection have these additional properties:
>
> **$promise**: the promise of the original server interaction that created this instance or collection.
>
> On success, the promise is resolved with the same resource instance or collection object, updated with data from server. This makes it easy to use in resolve section of $routeProvider.when() to defer view rendering until the resource(s) are loaded.
>
> On failure, the promise is resolved with the http response object, without the resource property.
>
> **$resolved**: true after first server interaction is completed (either with success or rejection), false before that. Knowing if the Resource has been resolved is useful in data-binding.

Access to the promise (`$promise`) is necessary if you want to be able to ensure a resource is loaded before instantiating the controller of the route, when using [`ngRoute.$routeProvider`](http://docs.angularjs.org/api/ngRoute.$routeProvider) or `uiRouter.$stateProvider`.

> `route.resolve`
> ... If any of these dependencies are promises, the router will wait for them all to be resolved or one to be rejected before the controller is instantiated.

Access to `$resolved` is useful if you want to data bind to an instance of a resource, and want to know if it is available.