Refresh login name on preferences

Logging in for the first time resulted in a `"Welcome, !"` message, even after
successfully authenticating. Now we update the greeting paragraph after auth.

To duplicate the problem:

* Make sure you're logged out of HH before starting the application
* Go to Preferences and click Yes to log in
* Enter valid credentials and log in
* **Note that the welcome message is still incorrect**

Subsequent app restarts would show the welcome correctly since it would already
be there in preferences when the app started, but this first login would hit the bug.