Retrieve user after successful login and display welcome

I updated the Application Route to use content instead of model as this is preferred method.

In the Application Controller I created a binding for the users email (this should be replaced with Name once that content exists in the User Table) which is then referred to from within the application.hbs

The important part here is the `sessionAuthenticationSucceeded` action on the Application Route. This event is fired by ember-simple-auth for exactly this kind of scenario. On a reload of the page, the `model` hook would be responsible for the user retrieval, but when a fresh login occurs the `sessionAuthenticationSucceeded` action will handle the user retrieval. 
The only reason I had the {{#if userName}} check was so "Welcome," didn't flash before "Welcome, <name>" appeared.  Any recommended way to do that?

This probably won't even be an issue if I cache the user object in local storage and update it in the background on page load.