Cache always skipped when redis client created earlier is specified

[mjgs]

When I pass a redis client I created earlier as an option the cache is always skipped.

Looking into the code the cache is always skipped when this.connected === false:

// ExpressRedisCache.js:

if ( self.connected === false || self.client.connected === false ) {
  return next();
}

This is actually the default value, which gets updated when the 'connect' event happens:

// ExpressRedisCache/route.js:

  this.client.on('connect', function () {
    this.connected = true;
    this.emit('connected', { host: this.host, port: this.port });
    this.emit('message', 'OK connected to redis://' + this.client.address);
  }.bind(this));

But since the 'connect' event happened earlier, this.connected never gets set correctly and so the cache is always skipped.

I have tested pull-request #96 in a fork and it fixes the issue, it would be great to have it merged in.