allow custom redis client for a more flexible setup

[sheldonxxxx]

All Submissions:

• [x] Have you followed the guidelines stated in CONTRIBUTING.md file?
• [x] Have you checked to ensure there aren't any other open Pull Requests for the desired changed?

Type of change

• [x] New feature (non-breaking change which adds functionality)
• [x] This change requires a documentation update

New Feature Submission:

• [x] Does your submission pass the tests?
• [x] Have you linted your code locally prior to submission?

Allow users to bring their own Redis client if they need a more complex connection setup