Support setting headers like Allow, Supported

[emiago]

more related on this PR #140

We could potentially have this headers or behavior part of client or server.

Ex server could detect what methods are supported and if caller wants those values could be passed on response.

Avoiding implicit behavior is desirable.

[SilvaMendes]

The idea would be to maintain compatibility of what the endpoint offers via header between peers, but it would be the server's responsibility to define whether the methods are supported or not, if not supported it would remove it from the response or even from the forwarding.

[emiago]

hey @SilvaMendes I suggest exploring this more from server API then. As in some cases I used this API to build that headers.
Checkout RegisteredMethods .
Unfortunately I think we would need better middleware implementation for supporting this.
For now I think it is on Caller user to build custom reply wrapper that inject this headers.