fix copyright status (fixes #29)

* add COPYING file with the GPL text
 * update copyright information in DAVAdmin's files

config/config.inc.php

@@ -1,6 +1,28 @@
 <?php
 /*
  * DavAdmin configuration file.
+ *
+ * @author Jan Dittberner <jan@dittberner.info>
+ * @version $Id$
+ * @license GPL
+ * @package DAVAdmin
+ *
+ * Copyright (c) 2007, 2008 Jan Dittberner
+ *
+ * This file is part of DAVAdmin.
+ *
+ * DAVAdmin 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.
+ *
+ * DAVAdmin 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 DAVAdmin; if not, see <http://www.gnu.org/licenses/>.
  */
 
 $davconfig = array(