Allow public countdowns to be viewed by logged out users

Summary: Fixes T5093. Ref T4830.

Test Plan:
  - As a logged out user, viewed a public countdown detail page.
  - (Tried to view a nonpublic one, got asked to login.)

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4830, T5093

Differential Revision: https://secure.phabricator.com/D9162

src/applications/countdown/controller/PhabricatorCountdownViewController.php

@@ -1,18 +1,18 @@
 <?php
 
-/**
- * @group countdown
- */
 final class PhabricatorCountdownViewController
   extends PhabricatorCountdownController {
 
   private $id;
 
+  public function shouldAllowPublic() {
+    return true;
+  }
+
   public function willProcessRequest(array $data) {
     $this->id = $data['id'];
   }
 
-
   public function processRequest() {
 
     $request = $this->getRequest();