When viewing a Ponder question, clear notifications about it

Summary: Fixes T3703. Clear question notifications when viewing a question.

Test Plan: Gave a question a token, logged in as author, saw notification, viewed question page, notification was marked read.

Reviewers: chad, btrahan

Reviewed By: chad

CC: aran

Maniphest Tasks: T3703

Differential Revision: https://secure.phabricator.com/D6723

src/applications/ponder/controller/PonderQuestionViewController.php

@@ -71,6 +71,7 @@ final class PonderQuestionViewController extends PonderController {
         'device' => true,
         'title' => 'Q'.$question->getID().' '.$question->getTitle(),
         'dust' => true,
+        'pageObjects' => array($question->getPHID()),
       ));
   }