feature: capture HTTP version in Request

[howardjohn]

This allows responding with info about the HTTP version.

Additionally, expanded a test to cover this.

Note: in the test, we assert resp.version(). However, for my use case I have test client --> reverse proxy under test --> wiremock, so I do not have direct access to the response from wiremock. Hence, I want to put more info about the request into the response body/headers.

[LukeMathWalker]

I agree with the change, but unfortunately it'd be a breaking change. So I'll set it aside for the next breaking release.