Research adding a supervisor to celery

[jason-upchurch]

User story

As a developer, I would like the ability for a supervisor process to oversee celery tasks so that corrective action can be taken outside of the app itself to preserve things like, for example, total number of times app was restarted, so that we don't potentially end up with infinite loops of restart attempts.

This issue stems from #4492, which originally discussed restarting the app from within a task.

Action items:

• Include flower, celery, and any other viable tools in research (related: set up flower to monitor celery activities on dev/stage/production #3665)
• Research the possibilities for adding a supervisor to celery
• Compare pros and cons of adding a supervisor

Completion criteria:

• Compile takeaways and recommendations regarding the possible addition of a supervisor to celery
• Open followup tickets as appropriate

[jason-upchurch]

closing pending research on best practices for placement of celery in different apps.

[jason-upchurch]

flower documentation: https://flower.readthedocs.io/en/latest/
supervisor documentation: http://supervisord.org/index.html