Add newlines and copyright notices.

app/Rules/IsBoolean.php

@@ -1,5 +1,27 @@
 <?php
 
+/**
+ * IsBoolean.php
+ * Copyright (c) 2018 thegrumpydictator@gmail.com
+ *
+ * This file is part of Firefly III.
+ *
+ * Firefly III is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Firefly III is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Firefly III. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
 namespace FireflyIII\Rules;
 
 use Illuminate\Contracts\Validation\Rule;