Include ngx_brotli (Brotli compression) module in NGINX package

[felixbuenemann]

Please consider including the eustas/ngx_brotli module in Passenger NGINX builds.

The module coexists nicely with NGINX' built-in gzip support and is disabled by default.

All modern browsers include support for brotli and it gives substantial savings for large resources like js, css, html, svg. (https://caniuse.com/#feat=brotli)

In my own tests I'm seeing around 20-25% savings on precompressed and minified js/css (brotli quality 11) and around 30-35% for on the fly html compression (brotli quality 5, similar speed to gzip default level).

If you do consider inclusion make sure to use the above mentioned fork by the main brotli developer eustas instead of the stale google/ngx_brotli module.

If you need help with packaging the module I'd be happy to make a PR.