* Add support for Brotli compression
* Allow compression algorithms to be added at runtime

Fix leftover Goji reference

* Using package http's already defined Method constants instead of redefining them

…TTP header (#367)

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

No transformations or conversions should be made to the resource. The Content-Encoding, Content-Range, Content-Type headers must not be modified by a proxy. A non- transparent proxy might, for example, convert between image formats in order to save cache space or to reduce the amount of traffic on a slow link. The no-transform directive disallows this.

The compress middleware removes `content-length` header before writing headers as the resulting length is not known at the time anymore. However it also does this if there is no suitable encoder found for the content type we have, forcing chunked encoding on every response.