unblocks #262

deficit accounting discussed with Emilio/Dhairya on 5.5.25 - after liquidation, check whether bad debt remains and if so, clear it by calling a function on Hub (either merged into hub restore method or a standalone separate method). clear away debt from the user/spoke position and add it to the deficit storage var on hub.

also include deficit into supply ex rate

• Miguel prefers 2 separate methods rather than merging into hub restore