Rather than custom netty server.

Harmonizes spring cloud contract versions to 1.2.4.RELEASE

fixes gh-2319

fixes gh-2851

fixes gh-2860

fixes gh-2854

* Handle GZip response from downstream with an empty body.

fixes gh-2807

* Always forward Content-Length from origin when set unless response is compressed and client does not support it

Fix for #2832

* Add test cases to assert behaviour with regards to the Content-Length header

Polishes tests.

fixes gh-2784