NewAPI receives an ampquri for routing messages, a redisURI for configuring workflows, and a host and a port for listening on.

NewMon initialises and returns a `Mon`, containing monitoring and metadata.

API contains routing and messagign capabilities.

ErrorResponse is a placeholder for outgoing errors in responses.

Mon is a container of Monitoring/ Metadata for json marshaling.

StarterRequest is a placeholder for incoming 'start workflow' requests.

StarterResponse is a placeholder for outgoing 'start workflow' responses.

StartWorkflow contains the message structure that kicking off a workflow expects in a master TaskManager.