Avoid too many levels of redirection through variables and
variables with studly-caps in favor of a single variable.
Default to the jessie and sid package, since that's what we'll
use going forward.  Avoid using regexes; this isn't really a
regex match, and we'll soon be able to delete the lenny case
anyway.

This is the (old) master branch along with the fixes to the
cron file permissions that Russ made.