(dev/core#179) Redis - Only send AUTH if there's a password

[totten]

Overview

The Redis driver always sends a password. That's well and good in production. However, if you're doing local development, the dev instance of redis may be configured to allow local-only, unauthenticated connections -- for which no password is available.

Before

If you don't use/need a password, the Redis driver sends an inappropriate AUTH command.

After

If you don't use/need a password, the Redis driver does not send an AUTH command.

[civibot]

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[colemanw]

Looks simple & safe.