no direct internet download from apt repositories, which over time will change or cease to exist. also migrate to gpg2 on newer ubuntu.
This should fix some tests, as a lot of them are dependent on deb.debian.org which no longer supports Debian 9 "Stretch". Instead we use archive.debian.org which will continue to contain "Stretch" packages for a long time.
Signed-off-by: Joshua Colson <joshua.colson@gmail.com>