Make dates/times more concise in Diffusion

Summary: I think I like this better -- but maybe right-aligned?

Test Plan:
{F1180295}

{F1180296}

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D15495

src/applications/diffusion/controller/DiffusionLastModifiedController.php

@@ -103,7 +103,7 @@ final class DiffusionLastModifiedController extends DiffusionController {
       $modified = DiffusionView::linkCommit(
         $drequest->getRepository(),
         $commit->getCommitIdentifier());
-      $date = phabricator_datetime($epoch, $viewer);
+      $date = $viewer->formatShortDateTime($epoch);
     } else {
       $modified = '';
       $date = '';