Add hub functionality to vr-xcon
Add hub functionality to vr-xcon

So this feels a little backwards but implementing a hub is just vastly
simpler than a learning bridge (well, switch) and I need ethernet
segments for emulating internet exchanges etc so here we are.

mzagozen/vrnetlab,plajjan/vrnetlab,bdreisbach/vrnetlab,plajjan/vrnetlab,mzagozen/vrnetlab,bdreisbach/vrnetlab