pkg_radd improvements

[James Frazer]

Will this fix the problem on 2.2.1 where it was trying to download from 
some host at evilprojects.net? (which didn't seem to resolve properly).

I can't remember the details, but I seemed to have some problems 
installing packages (which I should have documented better) which 
required some kind of override using $BINPKG_SITES.



Also, if you're on a 2.2.x system, pkg_radd will default to
pkgbox.dragonflybsd.org for downloads.  I have a redirectmatch rule now on
pkgbox that will send those requests to avalon, where the same packages
are available but the bandwidth is better.