Added a Paxos implementation.
I've added a fragile implementation of Paxos. It is not robust to
random node drops, it does not handle multiple proposers, and it can't
handle message loss.

Still, it works, and we can time it. To handle *real* Paxos, we would
need processes that can share state between clients and servers.
There are somme issues doing this in Python/Thrift (shared the blame).