* Use systemd socket activation
* Pass a new command line argument --systemd-socket-activation to the daemons if running on Linux
* Install .socket files
* Systemd services depend on their sockets
* Implement sd_listen_fds in OCaml
* Set FD_CLOEXEC in sd_listen_fds
* README: add comment about socket paths
* Linux systemd scripts: Rename albatross_stat -> albatross_stats
by Lwt_unix.wait_read (in read_console, called asynchronously in a fresh task)
and only then convert to a Lwt_io.t (of_fd ~mode:Input) -- thanks to @cfcs
This allows albatross to be run on Linux, where the former code lead to:
- open FIFO
- read <- EOF (although no writer was connected yet)
this works nicely around ocsigen/lwt#741