Experiment with Docker Secrets

[nikola-rados]

Is your feature request related to a problem? Please describe.
Currently we use environment variables to define some of our secret credentials. This design pattern is from the 12 factor app, but the ideas being that paradigm have shifted a bit since.

Describe the solution you'd like
We can use docker swarm to produce secrets. This also would mean that we need to update the code to handle these secrets. May need to be done directly in p2a-rule-engine.