Feature #3076: migrate to new (2018-03) server "host2.osmocom.org"
migrate ftp to new server
ftp.osmocom.org hosts manuals and other downloads. Migrate it to the new server.
The current setup with one "user" per directory (api/docs/binaries/...) doesn't really map well to a static docker container. So either we have to move away from that one-user-with-ssh-key-per-directory for uploads, or we have to run it in a lxc rather than a docker container.
OTOTH, the number of users is fairly static, so we could actually create them (and add their ssh keys) from within a Dockerfile, too.