Add Content-Encoding 'br' for brotli support
A compression algo which compresses as good as lzma but with much faster compression and decompression speed. See Mozilla discussion: https://bugzilla.mozilla.org/show_bug.cgi?id=366559 https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding https://github.com/bagder/libbrotli https://hacks.mozilla.org/2015/11/better-than-gzip-compression-with-brotli/