support gzip/deflate requests

[davidchase]

support gzip/deflate requests using zlib

[davidchase]

i think it maybe better to provide as add-on like

const { unzip } = require('zlib')
const unzipStream = fromCb(unzip)
// ...
const f = compose(map(JSON.parse), map(toString), chain(unzipStream))

f(bufferStream)

[davidchase]

related to #4