WIP: Naive failover handler
An http admin interface. The first function is the ability for a naïve failover whereby an admin can do
curl -X POST localhost:9093/failover -d '{"new_primary":"backup"}'
A long term solution may not be an http server, but this is a nice stop gap to allow us to get the failover logic demo-able.
addresses: #1615 (closed)
Edited by John Cai