Inter-op test for the Go middleware (from Improbable)

[wenbozhu]

See #60

@mwitkow

[fengli79]

I plan to create a set of interop tests, while the middleware is pluggable. Today, it can be nginx and envoy. A go proxy should also be able to be integrated with limited changes.

[mwitkow]

@fengli79 happy to help out if you need a hand or find something junky on our side :)

[johanbrandhorst]

Since the merge of #121, should this be possible to test again?

[johanbrandhorst]

Bump. We need clarity on how this client interops with the Improbable backend proxy.

[johanbrandhorst]

I desperately think this needs to be completed before GA (if you're still aiming for October).

[stanley-cheung]

Added a demo to show interoperability with the Improbable gRPC Web Go Proxy

docker-compose up echo-server grpcwebproxy binary-client