Log Message:
Import caff from the Debian PGP Tools.  

caff is a script that helps you in keysigning.  It takes a list of
keyids on the command line, fetches them from a keyserver and calls
GnuPG so that you can sign it.  It then mails each key to all its
email addresses - only including the one UID that we send to in each
mail.

Features:
 * Easy to setup.
 * Attaches only the very UID that we send to in the mail.
 * Prunes the key from all signatures that are not self sigs and
   not done by you, thereby greatly reducing the size of mails.
 * Sends the mail encrypted if possible, will warn before sending
   unencrypted mail (sign only keys)
 * Creates proper PGP MIME messages.
 * Uses separate GNUPGHOME for all its operations.