WIP: Implement Redis queue system

[btylerburton]

User Story

In order to achieve stability in the Harvesting 2.0 pipeline, data.gov wants to implement a Redis queue system.

Acceptance Criteria

[ACs should be clearly demoable/verifiable whenever possible. Try specifying them using BDD.]

• GIVEN a user/process wishes to initiate a harvesting job
  THEN the job processing will be managed by a Redis queue

Background

[Any helpful contextual notes or links to artifacts/evidence, if needed]

The Redis queue was defined here: #4314

Security Considerations (required)

[Any security concerns that might be implicated in the change. "None" is OK, just be explicit here!]

None

Sketch

• Implement pre-defined Redis queue in ETL pipeline

[hkdctol]

TO DO: this might be two tickets, one for job queue and one for the record queue.