apt-key doesn't add long keys in deb6

You can feed the command the long key, but it truncates it to add the
key. This causes issues due to the short-key collision with the
puppetlabs key. So, test with a different key on debian 6.
Merge pull request #367 from mhaskel/deb6_apt-key_workaround

apt-key doesn't add long keys in deb6