Use REDIS_DB in streaming (#3094)

streaming/index.js

@@ -92,6 +92,7 @@ if (cluster.isMaster) {
   const redisParams = {
     host:     process.env.REDIS_HOST     || '127.0.0.1',
     port:     process.env.REDIS_PORT     || 6379,
+    db:       process.env.REDIS_DB       || 0,
     password: process.env.REDIS_PASSWORD,
     url:      process.env.REDIS_URL      || null
   }