Fix ordering in systemd service file

See: https://bugs.archlinux.org/task/41338

Docker-DCO-1.1-Signed-off-by: Sébastien Luttringer <seblu@seblu.net> (github: seblu)
Systemd .service should install .socket

And remove the WantedBy directive.

See: https://bugs.archlinux.org/task/41338

Docker-DCO-1.1-Signed-off-by: Sébastien Luttringer <seblu@seblu.net> (github: seblu)
Systemd service should not restart on failure

This should not be done by default but used by adminsys with a drop-in.d file,
for buggy daemons which crash without known fixes.

Docker-DCO-1.1-Signed-off-by: Sébastien Luttringer <seblu@seblu.net> (github: seblu)
Merge pull request #7257 from seblu/master

Improve systemd units