add redis integration for cache

[danielfogt]

a minimum configuration for redis integration for cache (resolves #328)

[RadoRado]

Hello @danielfogt :wave:

Thank you for opening this!

I'd like to give it a thought, before merging.

Caching is usually something that comes usually at a later stage for a project.

And usually, you have 2 options:

1. Leverage the Django's cache framework / backend.
2. Use a plain Redis client.

I've seen & done both.

That's why I want to think thru it.

One of the project that we are currently working on, will soon require cache, which will be a good point for evaluating.

Cheers!