Use Amber::Pipe::Static handler to set http response cache headers
Use Amber::Pipe::Static handler to set http response cache headers

Enables caching of static files in `public/` dir which
will improve page load time and prevent delays in applying css/js to the
dom.

https://devcenter.heroku.com/articles/increasing-application-performance-with-http-cache-headers

crystal-community/crystal-ann