Provide an application link for Ponder Answer PHID type

Summary: Ref T9625. I want this to be fixed ASAP hence here's the patch.

Test Plan:
 - ~~Apply D14323~~ (This patch was made before it was merged)
 - Apply this patch
 - voila! Now I see the Ponder answer has correct logo.

{F906357}

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, revi

Maniphest Tasks: T9625

Differential Revision: https://secure.phabricator.com/D14331

src/applications/ponder/phid/PonderAnswerPHIDType.php

@@ -8,6 +8,10 @@ final class PonderAnswerPHIDType extends PhabricatorPHIDType {
     return pht('Ponder Answer');
   }
 
+  public function getPHIDTypeApplicationClass() {
+    return 'PhabricatorPonderApplication';
+  }
+
   public function newObject() {
     return new PonderAnswer();
   }