Promise based authentication status

This update includes a promise based method to determine authentication status.  This can be utilized in the resolve section of routes and prevent routes from being loaded if user is not authenticated, or ensure that the auth status is known before the route is loaded.  Events are now broadcasted from the djangoAuth service to indicate when the authentication status changes: djangoAuth.logged_in and djangoAuth.logged_out.  Appropriate examples and documentation have been included as well.