Working solution

A full Message Broker development environment is required to do a functional test. A general code review is welcomed.

See https://github.com/DoSomething/messagebroker-config/blob/master/mb-config.inc as the source of the exchange and queue configuration settings.

This has been tested with a sample CSV file that successfully produced entries in the importUser queue.
You could probably just grab the first line of the CSV to create the mapping array actually.