Updated authorship and copyright information

This commit updates all authorship and copyright information to include a
standard header that references the AUTHORS and CREDITS file. This standard
header was written by the Debian legal team at the request of Franck Joncourt.

lib/fko_encode.c

@@ -3,13 +3,13 @@
  *
  * File:    fko_encode.c
  *
- * Author:  Damien S. Stuart
- *
  * Purpose: Encodes some pieces of the spa data then puts together all of
  *          the necessary pieces to gether to create the single encoded
  *          message string.
  *
- * Copyright 2009-2013 Damien Stuart (dstuart@dstuart.org)
+ *  Fwknop is developed primarily by the people listed in the file 'AUTHORS'.
+ *  Copyright (C) 2009–2014 fwknop developers and contributors. For a full
+ *  list of contributors, see the file 'CREDITS'.
  *
  *  License (GNU General Public License):
  *