Support for socket activation

[axos88]

Hello,

I tried googleing around, but it seems there is no support for socket activation in spray-can.

https://www.freedesktop.org/software/systemd/man/systemd.socket.html
http://0pointer.de/blog/projects/socket-activation.html (quite old though)

Is this something that can be added easily, or hacked into it from the client side?

[axos88]

@jrudolph?