Update copyright notices, update German language.

app/Http/Controllers/Auth/RegisterController.php

@@ -1,4 +1,12 @@
 <?php
+/**
+ * RegisterController.php
+ * Copyright (C) 2016 thegrumpydictator@gmail.com
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE file for details.
+ */
+declare(strict_types = 1);
 
 namespace FireflyIII\Http\Controllers\Auth;
 
@@ -111,7 +119,6 @@ class RegisterController extends Controller
      */
     public function showRegistrationForm(Request $request)
     {
-        // TODO move to FireflyConfig
         $showDemoWarning = env('SHOW_DEMO_WARNING', false);
 
         // is allowed to?