HTTP Caching setup

https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching#Cache_validation

https://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html

http://www.web-caching.com/mnot_tutorial/

https://tools.ietf.org/html/rfc7234

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control

https://developers.google.com/speed/docs/insights/LeverageBrowserCaching

https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/http-caching