Tweak alert states in header a bit more

Summary: The sky blue colors in the alerts was problematic in other color headers (not black). Rather than hand tweak each color, just going with white seems best. There is also a small animation now, which you may or may not like. It is playful and enjoyable to me at least.

Test Plan: Tested various header colors with and without alert notifications.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11838

src/view/page/menu/PhabricatorMainMenuView.php

@@ -144,7 +144,7 @@ final class PhabricatorMainMenuView extends AphrontView {
         'meta'  => array(
           'map' => array(
             $header_id => 'phabricator-application-menu-expanded',
-            $button_id => 'sky',
+            $button_id => 'white',
           ),
         ),
       ),
@@ -207,7 +207,7 @@ final class PhabricatorMainMenuView extends AphrontView {
         'meta'  => array(
           'map' => array(
             $header_id => 'phabricator-search-menu-expanded',
-            $button_id => 'sky',
+            $button_id => 'white',
           ),
         ),
       ),