Fix double escaping in Pholio subscribers

Summary:
Fallout from D4822. We now escape text by default, and imploding links causes double-escaping. See here for details:

http://www.phabricator.com/docs/phabricator/article/Rendering_HTML.html

Test Plan: {F32100}

Reviewers: ljalonen, chad, btrahan, vrana

Reviewed By: ljalonen

CC: aran

Differential Revision: https://secure.phabricator.com/D4878

src/applications/pholio/controller/PholioMockViewController.php

@@ -145,7 +145,7 @@ final class PholioMockViewController extends PholioController {
       foreach ($subscribers as $subscriber) {
         $sub_view[] = $this->getHandle($subscriber)->renderLink();
       }
-      $sub_view = implode(', ', $sub_view);
+      $sub_view = array_interleave(', ', $sub_view);
     } else {
       $sub_view = phutil_tag('em', array(), pht('None'));
     }