I sent this out a while ago and didn't really receive any comments then
kind of forgot about it.  These changes are not critical, but are really
necessary for certain situations and testing to make things behave like
they really should:

* It allows a BMC to be created with no UUID, returning an error, which
  is the behavior of many BMCs in the world.
* It lets the user set the UUID to a fixed value.

Some software using IPMI will get confused if it gets different UUIDs
from what should be the same device, which is what happens now if qemu
quits and restarts.

So sending out for review again.

Thanks,

-corey