Declare used properties

Summary: Also fix couple of other errors.

Test Plan: Executed controllers.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3627

src/applications/auth/controller/PhabricatorOAuthDiagnosticsController.php

@@ -19,6 +19,8 @@
 final class PhabricatorOAuthDiagnosticsController
   extends PhabricatorAuthController {
 
+  private $provider;
+
   public function shouldRequireLogin() {
     return false;
   }