Change `Redis.makeConnection` to `RedisConnection.connect`

Motivation:

During proposal review, feedback was provided that the discoverability of the factory method of RedisConnection was poor outside of documentation.

Modifications:

Move Redis.makeConnection to RedisConnection.connect. As part of this, RedisConnection has been moved to its own file as well.

Result:

Users should have an easier time discovering how to easily create RedisConnections.

This contributes to #47 (closed).