A. Two new environment vars:
1. WEB_ROOT
the web server will serve from / (/var/www/html) or a deeper directory
2. ARCH
if you only want to mirror amd64 you can use deb-amd64 instead of deb
B. Setup clean.sh to work from postmirror.sh. If postmirror.sh already
exists it is not touched. postmirror.sh can also be
edited to add other commands. It's in /var/www/html/var << this is the
way that apt-mirror works
C. Other little changes.