Add support for temp usernames and an interstitial to confirm username

When a user now logs in for the first time for any external auth (LDAP, JWT, Keystone, Github, Google, Dex), they will be presented with a confirmation screen that affords them the opportunity to change their Quay-assigned username.

Addresses most of the user issues around #74

static/js/app.js

@@ -189,6 +189,9 @@ quayApp.config(['$routeProvider', '$locationProvider', 'pages', function($routeP
     // Privacy
     .route('/privacy', 'privacy')
 
+    // Change username
+    .route('/updateuser', 'update-user')
+
     // Landing Page
     .route('/', 'landing')