FIX: You can click to see your own PMs from flags

Also refactors post action users to be a new object type since they can
have `post_url` which is not a field of a `User`

config/routes.rb

@@ -365,6 +365,7 @@ Discourse::Application.routes.draw do
 
   get "excerpt" => "excerpt#show"
 
+  resources :post_action_users
   resources :post_actions do
     collection do
       get "users"