No Redis client connected. Verify cache settings. - Update with debug steps

Problem/Motivation

When setting up this module, the error message "No Redis client connected. Verify cache settings." is not very helpful at all.

Steps to reproduce

Enable the module and navigate to /admin/reports/redis

Proposed resolution

Add in more detailed feedback as to what settings are wrong. I'd suggest the following:

• Current settings (host, post, Redis extension installed, Predis installed, etc)
• Error back from the Redis connection

Cheers

Tom