move render-blocking js to below the fold.

client-side performance enhancement. 

See: [Google's PageSpeed Insight for redis.io](https://developers.google.com/speed/pagespeed/insights/?url=http%3A%2F%2Fredis.io%2F)
Merge branch 'patch-1' of https://github.com/bradoyler/redis-io
No need for `async`.