basic handling of gzip content-encoding on requests as per https://gi…

[matt-mercer]

as per #31
really basic handling for gzip content-encoding on requests ...

new test added: message Make JSON request with gzip Content-Encoding, and test that json is in the output.

manual testing

echo -n '{"a":"b"}' | gzip | curl -s -X POST -H "Content-Encoding: gzip" -H "Content-Type: application/json" --data-binary @- http://localhost:8080/

[mendhak]

Wow! OK let me give this a try this weekend thanks