a systemd-journald compatible log output on stderr (#1912)

* a systemd-journald compatible log output on stderr

based on the stderr logger but changed:
- doesn't output the timestamp, the journal already has a timestamp
- output the log level as <num> where num is defined as in `sd-daemon(3)`

https://www.freedesktop.org/software/systemd/man/sd-daemon.html
2 files changed