Implement new auth login flow and login validation controller

Summary:
Ref T1536. None of this code is reachable.

Implements new-auth login (so you can actually login) and login validation (which checks that cookies were set correctly).

Test Plan: Manually enabled FB auth, went through the auth flow to login/logout. Manually hit most of the validation errors.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1536

Differential Revision: https://secure.phabricator.com/D6162

src/applications/auth/controller/PhabricatorAuthStartController.php

@@ -138,20 +138,9 @@ final class PhabricatorAuthStartController
   }
 
   private function renderError($message) {
-    $title = pht('Authentication Failure');
-
-    $view = new AphrontErrorView();
-    $view->setTitle($title);
-    $view->appendChild($message);
-
-    return $this->buildApplicationPage(
-      $view,
-      array(
-        'title' => $title,
-        'device' => true,
-        'dust' => true,
-      ));
+    return $this->renderErrorPage(
+      pht('Authentication Failure'),
+      array($message));
   }
 
-
 }