Add possibility to configure socket timeout

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• Version: 2.8.0
• Platform: Node.js 8.11.1on node:8-alpine docker image on Kubernetes 1.9.3
• Description: On different environments different default tcp timeouts might occur. Currently AFAIK node-redis doesn't allow to configure socket timeout. I find it problematic on my prod environment, when redis server (behind a k8s service, a kind of load balancer) is down for couple of seconds, node_redis client is hanged trying to reconnect. Even though redis starts responding, the client is still hanged until it reaches a timeout which seems to be 130 seconds in my case.
  I would like to configure redis client to wait only a given timeout.
  The deprecated param connect_timeout seems to not work as expected.
  Is there any way to configure socket timeout in node-redis?

No file or test is named in the report; start by tracing node-redis connection setup and the deprecated connect_timeout option. Confirm how socket timeout is configured, then verify with a test that a stalled Redis connection honors the configured limit and reconnects without hanging.