Fixing some small dspam oddities

The included /etc/dspam/dspam.conf file still had "Home" set to /var/spool/dspam. Since there's some sensitive info in the logs there, I figured it'd be best to change that directive to place stuff in /decrypted-mail/dspam (I figured this is where you originally intended, since you were creating the decrypted-mail/dspam folder already).

Second, there was a really strange bug with dspam, where it *always* placed the DSPAM signature in the message body, even though the config file had signatureLocation set to 'headers'. Only way I was able to fix it was to remove the trailing comment from the signatureLocation line in /etc/dspam/default.prefs.

Let me know if there's anything to improve here :-)