As 284, part 1 - find a created server on Nova (ready for review)

This change is bigger than I thought, so I am trying to break it up into bits.  This part just provides the functionality to check Nova for an exact server that matches a given server config, created around a certain time.

Question for the next part - should we wait at all after getting a 500 or 401 response back from Nova from creating a server, before checking Nova to see if a server was created? 
Hm... no actually I think you're, the chance of collision is pretty rare given the numbers and given that it's scoped to a single tenant in Nova.

I was mostly worried about (1) the amount of randomness on our cloud servers and (2) that nova may return wrong data.  I think I'll remove the timestamp check and limit the extra checking to the group ID, whih is a