Fixup pi config

The SuNSS pi image needs a bit more tweaking.

• There is a bug in raspbian which keeps the dhcp-fed ntp servers from being registered and actually used by systemd-timesyncd. I have been using the last suggestion in https://www.raspberrypi.org/forums/viewtopic.php?p=1339653 on the temps boards.
• /etc/hostname should be set to localhost, I believe, Or sunss. Various things want to resolve the "pfssunss" name and are failing.
• need to add the tcp_server.py listener to the image and have it be launched at @reboot. That is in the git repo.
• it is hard to keep /usr/local/bin itself as a git repo, and that path is used in the code. So add a top-level install script to the repo.