chore(redis): enable redis hostname to be set through env variable

Author: rskaar

lib/redis.js

@@ -1,3 +1,7 @@
 const Redis = require('ioredis');
 
-module.exports = new Redis(6379, 'redis');
+const redisHostname = process.env.REDIS_HOSTNAME
+  ? process.env.REDIS_HOSTNAME
+  : 'redis';
+
+module.exports = new Redis(6379, redisHostname);