[sheepdog] [PATCH] sheep: add a kill node operation

[Dietmar Maurer]

> For now, we will get a 1) epoch_mismatch error, or 2) OBJ is being recovery
> for this case and gateway node will retry the request when the epoch
> matches (1), targeted node will re-queue the request locally when OBJ is
> recoveried (2).

Let's assume a complete recovery takes about 2 hours. Does that mean my VMs are
blocked for 2 hours (instead of continue operation on other nodes)?

- Dietmar