Migrate project blurb/description to standard custom field storage

Summary: Ref T4379. Major goal here is to remove `ProjectProfile` so all edits use ApplicationTransactions. This also makes things more flexible, allowing users to disable this field if they don't like it.

Test Plan: Ran migration, verified data survived, edited/created projects, reordered fields.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4379

Differential Revision: https://secure.phabricator.com/D8182

src/applications/project/controller/PhabricatorProjectProfileController.php

@@ -271,13 +271,6 @@ final class PhabricatorProjectProfileController
       PhabricatorCustomField::ROLE_VIEW);
     $field_list->appendFieldsToPropertyList($project, $viewer, $view);
 
-    $view->addSectionHeader(pht('Description'));
-    $view->addTextContent(
-      PhabricatorMarkupEngine::renderOneObject(
-        id(new PhabricatorMarkupOneOff())->setContent($profile->getBlurb()),
-        'default',
-        $viewer));
-
     return $view;
   }