base.install: add update sources
base.exclude: exclude .ssh, .ansible and .bash_history in /root
functions: generate a compressed archive.
init: try to download archive from an http server before trying rsync
pxe.install: maximum compression to reduce the size
upload.py: simplify logging.
docker: fix missing piece (abort under Debian, add exclude)
functions: only generate archive when the exit code of the script was 0