decouple redis from netbox

[mmguero]

redis is used by NetBox but will shortly be used by strelka (#485) as well. I don't know that there's any tight coupling, but we should decouple redis from NetBox as far as the containers/environment variables/etc. goes. NetBox will still use it, but other things should be able to as well. This is more about code organization than functional changes, I think.

[mmguero]

Just need to double-check kubernetes functionality before closing.