Add a breadcrumbs element

Summary:
Add a basic breadcrumbs element, and implement it in Paste.

This needs some polish but is most of the way there.

Test Plan:
{F26443}
{F26444}
{F26445}

(This element is not visible on devices.)

Reviewers: chad

Reviewed By: chad

CC: aran, btrahan

Maniphest Tasks: T1960

Differential Revision: https://secure.phabricator.com/D4087

src/applications/paste/application/PhabricatorApplicationPaste.php

@@ -22,8 +22,9 @@ final class PhabricatorApplicationPaste extends PhabricatorApplication {
     return array(
       '/P(?P<id>[1-9]\d*)' => 'PhabricatorPasteViewController',
       '/paste/' => array(
-        '' => 'PhabricatorPasteEditController',
-        'edit/(?P<id>[1-9]\d*)/' => 'PhabricatorPasteEditController',
+        ''                        => 'PhabricatorPasteListController',
+        'create/'                 => 'PhabricatorPasteEditController',
+        'edit/(?P<id>[1-9]\d*)/'  => 'PhabricatorPasteEditController',
         'filter/(?P<filter>\w+)/' => 'PhabricatorPasteListController',
       ),
     );