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>

ui-clone.c

@@ -1,7 +1,7 @@
 /* ui-clone.c: functions for http cloning, based on
  * git's http-backend.c by Shawn O. Pearce
  *
- * Copyright (C) 2008 Lars Hjemli
+ * Copyright (C) 2006-2014 cgit Development Team <cgit@lists.zx2c4.com>
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)