[DRE-maint] unicorn: native systemd service

[Eric Wong]

Adding unicorn-public at bogomips.org to Cc:

Those of you who haven't followed along on the unicorn at packages.debian.org
list can catch up here:
http://lists.alioth.debian.org/pipermail/pkg-ruby-extras-maintainers/2015-June/024539.html

Dmitry: unicorn upstream here, is there anything in unicorn itself
can do to make systemd integration easier?

I haven't had much interest or time to dig into systemd, but I'm willing
to put some effort into making unicorn work more smoothly with systemd
(and any other Free Software process managers/init systems).

So far unicorn.git has documented the UNICORN_FD environment variable in
the manpage in commit 548e1e67d314f6ebd17df37ece0ee20632462f6f [1]
and support SIGWINCH (kill children) in
commit a6077391bb62d0b13016084b0eea36b987afe8f0 [2]

I think that should be sufficient, but maybe there's more.
Thanks.

[1] http://bogomips.org/unicorn.git/patch/?id=548e1e67
[2] http://bogomips.org/unicorn.git/patch/?id=a6077391