address a few nits

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Fix io.Reader ambiguity on EOF in progressreader

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Fix ordering in systemd service file
Systemd .service should also install .socket
Systemd servide should not restart on failure

This should not be done by default but with a drop-in.d file.