Scale-out servers

[JWMB]

Currently we are using a single server instance for admin + sync/aggregation.
We want to distribute the workload on multiple instances, and scale up/down the number depending on workload. Ususally 95% of traffic happens during some 30 hrs / week, the rest of the time (72% of a week), one small instance should be enough

• A few code paths rely on a singleton instance - address those
• Set up load balancer rules (ARRAffinity cookie is enough?)
• Set up load tests