Add extension system for supporting other backends

[ntdef]

The code is modular enough to support other backends, but to swap out a backend you would actually have to modify the codebase as-is. Ideally, you should be able to point to point to a Python class at startup and use that as the storage backend.

It's probably worthwhile to look into how Flask/Gunicorn does this when looking for the app object.

[bburns632]

Thank you for your interest. However, this project will be archived shortly. More details in #77 .