I tried to summarize my thoughts on a communication protocol between
master, slaves and spawner here
https://gist.github.com/rotanov/a22dbdba7af6475cfb36
There are some unclear points. I'm inclined to eradicate asynchrony from
the protocol so master will never have to parse anything since he's sure
to await response from the slave he sent message to. And it will make
spawner implementation a little bit easier.
