make recommendation they sign in and retry

app/controllers/application_controller.rb

@@ -32,7 +32,11 @@ class ApplicationController < ActionController::Base
   end
 
   def handle_unauthorized
+    if authenticated?
       head :forbidden # TODO make this better
+    else
+     redirect_to new_user_session_path, notice: "Try signing in to do that." 
+    end
   end
 
 private