Replace networking stack with etcd-based approach

[noonio]

Why

We saw in the recent spike #1591 that Raft (via etcd) provides benefits over our present approach: it allows for more instability in the client connections, and more transparency in what is happening.

We would like a resiliant and reliable networking layer, and this seems like a viable approach.

What

• Use learnings from the spike to integrate raft via etcd
• (Probably) don't rely on etcd-as-a-binary, use some kind of Haskell binding

How

TBD