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.
The client --test mode decrypts SPA packet data as a final step, but get_keys()
was being called to re-acquire the encryption/HMAC keys. This commit reuses
the same keys that were supplied for SPA packet encryption/authentication
because the most important code to test is not get_keys() but rather libfko
encryption/decryption/authentication operations.
