Add timezone support

Summary:
Allows user-configurable timezones. Adds a preference panel, and migrates to the
new date rendering in easily-modified areas of the code. ***In progress***.

Test Plan:
Check database to make sure the field is being changed when the settings are
changed; check affected views to see how they render times.

Reviewed By: epriestley
Reviewers: epriestley
CC: aran, epriestley, toulouse
Differential Revision: 475

src/applications/diffusion/controller/home/DiffusionHomeController.php

@@ -19,6 +19,8 @@
 class DiffusionHomeController extends DiffusionController {
 
   public function processRequest() {
+    $request = $this->getRequest();
+    $user = $request->getUser();
 
     $shortcuts = id(new PhabricatorRepositoryShortcut())->loadAll();
     if ($shortcuts) {
@@ -94,8 +96,8 @@ class DiffusionHomeController extends DiffusionController {
       $date = '-';
       $time = '-';
       if ($commit) {
-        $date = date('M j, Y', $commit->getEpoch());
-        $time = date('g:i A', $commit->getEpoch());
+        $date = phabricator_date($commit->getEpoch(), $user);
+        $time = phabricator_time($commit->getEpoch(), $user);
       }
 
       $rows[] = array(