Pass a connection string instead of separate parameters

Created by: afm-sayem

Fixes #306 (closed)

It's very convenient to pass the environment variable for the Redis connection than parsing the URL everytime you want to create a connection. Saves some effort in parsing and passing authentication separately.

I haven't written any test for authentication since I'm unsure how to spawn a Redis server with authentication for running this test. Any help in that regard will be appreciated.