Update copyright information

* Name "cgit Development Team" as copyright holder to avoid listing
  every single developer.

* Update copyright ranges.

Signed-off-by: Lukas Fleischer <cgit@crytocrack.de>

scan-tree.c

@@ -1,7 +1,6 @@
 /* scan-tree.c
- * 
- * Copyright (C) 2008-2009 Lars Hjemli
- * Copyright (C) 2010-2013 Jason A. Donenfeld <Jason@zx2c4.com>
+ *
+ * Copyright (C) 2006-2014 cgit Development Team <cgit@lists.zx2c4.com>
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)