passive-dns patch

    Attached is a patch for passive-dns.bro .  The patch adds some
variables for doing scp uploads, variabalizes the rotation interval &
uses a boolean value handle processing locally or scping to a remote
host.  The last change is using ./ to refer to dns-ans-query.bro so I
could move the passive-dns policy into a directory & use __load__.bro
whitespace edits
scp -> sftp, change default.

change scp to sftp to match the postprocessor name.
set the default to False