v0.3.7 — rendezvous account affinity

• A conversation's home pool account is picked by rendezvous hashing instead of hash % pool size (#11). Adding or removing an account now moves only ~1/N of live conversations, and a failing account's conversations spread over the rest of the pool instead of all landing on its neighbour.
• Upgrading from v0.3.6 moves most conversations to a new home account once (one uncached turn each).