Only allow primary domain for RS

Replace user addresses with usernames in the respective URLs

config/routes.rb

@@ -78,8 +78,8 @@ Rails.application.routes.draw do
 
   namespace :rs do
     resource :oauth, only: [:new, :create], path_names: {
-      new: ':useraddress', create: ':useraddress'
-    }, controller: 'oauth', constraints: { useraddress: /[^\/]+/}
+      new: ':username', create: ':username'
+    }, controller: 'oauth'
     get 'oauth/token/:id/launch_app' => 'oauth#launch_app', as: :launch_app
   end