use the $http and $q services: getCurrentUser, isAuthenticated, currentUser

getCurrentUser - fetches the current user and caches the currentUser •
isAuthenticated - asks whether we have fetched an authenticated user •
currentUser - calls the cached current_user
load this current user when the controller is instantiated or we can load it when the controller loads
fetch the result of the service request in the HomeController by using the injected value.
update our view, we can see the user is populated for us
remove the extra tab space
Merge branch 'chapter2.4-interacting-session-api' into chapter2-angular-in-rails-asset-pipeline