Check that copy requests succeed or fail the event processing
README.md: `INSTALL` -> `INSTALL.md`
Switch to RabbitMQ from Pgq

Instead of using PgQ, use RabbitMQ as the messaging system. This commit also
introduces automatic retrying of events. For information on this, please see
[Arch.md](Arch.md).
Move Arch.md to Architecture.md
Replace carton instructions with local::lib instructions.
Updating daemontools service to match production
proxy-pgq: New script to proxy from PgQ to RabbitMQ

This script does the minimal amount of work to shuffle data from
PgQ into RabbitMQ. We're going to need this to bulk load RabbitMQ
with any outstanding events in PgQ when we switch to RabbitMQ
Merge branch 'check-copy'
Merge branch 'rabbitmq'