Consider alternative CASPaxos implimentation instead of Gossip

[AceHack]

I realize this would probably be a new Shielded.CASPaxos, not a change to this library but would love to see Shielded combined with CASPaxos

More info: https://arxiv.org/abs/1802.07000 https://github.com/gryadka/js https://github.com/peterbourgon/caspaxos http://rystsov.info/

[jbakic]

Hello! I think this might be interesting for the consistent backend. Currently it uses a very simple 2PC, which I chose, honestly, merely for the simplicity. I'll keep this open to remind me to have a deeper look at this when I find the time. Thank you!