Support IIPs about msgflo

[jonnor]

Now that we have startup templating in, maybe we can/should pass IIPs through the commandline?
mycommand --initials #INITIALS, where INITIALS is a JSON object { portA: "iipB", portB: "iipB" }.
This assumes that order of IIPs does not matter, which ought to be fine?

[bergie]

@jonnor NoFlo sends IIPs in order of appearance after all processes have started, but in general I think order doesn't matter. A potential problem is, we'd need to send them to each process of the same role (which can start and shut down arbitrarily). Maybe can be done based on discovery messages?

[jonnor]

@bergie I'm proposing passing them via the commandline at process startup.

This will of course not work for changing the graph at runtime, but is much better than nothing.