make PonderQuestionQuery policy aware

Summary: wanted to play with some policy stuff as its been a bit. Turns out you can't edit questions so this is very silly "so long as you are a user you can view it" policy. also sorry if you have a diff or twelve out for this in your sandbox(es).

Test Plan: loaded up ponder and clicked about

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2113

Differential Revision: https://secure.phabricator.com/D4163

src/applications/ponder/controller/PonderFeedController.php

@@ -34,7 +34,8 @@ final class PonderFeedController extends PonderController {
         $pager->setOffset($request->getStr('offset'));
         $pager->setURI($request->getRequestURI(), 'offset');
 
-        $query = new PonderQuestionQuery();
+        $query = id(new PonderQuestionQuery())
+          ->setViewer($user);
 
         if ($this->page == 'feed') {
           $query