Handle Shelley genesis SPOs

[sandtreader]

In the Shelley genesis file there are genDelegs which have VRFkeys for the IOG nodes which were used until the SPOs were all up and registered. These need to be sent out as fake SPO registrations with the valid keys but no other data, and flagged to do the right thing in the reward calculation (which we think means they probably get ignored).

The GenesisBootstrapper can do this when it sees epoch 208 start, similar to what it will do on parameter updates in #37.

[sandtreader]

It will no longer do the parameter updates in the new version of #37, but it can still do the fake SPOs.