Pass object to redis createClient

[JohnMcLear]

As per discussion in ether/etherpad-lite#4693

[rhansen]

I wonder if we should do this instead:

  if (this.settings.socket) {
    // Deprecated, but kept for backwards compatibility.
    this.client = redis.createClient(this.settings.socket,
        this.settings.client_options);
  } else if (this.settings.client_options) {
    // Deprecated, but kept for backwards compatibility.
    this.client = redis.createClient(this.settings.port,
        this.settings.host, this.settings.client_options);
  } else {
    // This is the preferred way to configure the client.
    this.client = redis.createClient(this.settings);
  }

Also, the minor version should be bumped in this PR.

[rhansen]

Also, init() shouldn't call auth() in the redis.createClient(this.settings) case.