Fixes headers/trailers being lost when grpc-status is non-zero.  (#226)
Fixes headers/trailers being lost when grpc-status is non-zero.  (#226)

* rawOnHeaders now called even on grpc errors, code defaults to grpc-status if available, headers provided to rawOnError

improbable-eng/grpc-web,improbable-eng/grpc-web,improbable-eng/grpc-web,improbable-eng/grpc-web,improbable-eng/grpc-web