Support hyperlinks from responses

From the discussion on slack: the solution needs to expose an option to allow `client.fetch` to serialize responses.

@mglaman → I’m still quite apprehensive to change the return type of client.fetch and I don’t see a clean way of adding this to that method. However, I can add a getResourceByURL or somesuch method that will take in a full URL and return the content serialized if the serializer is available. Is that reasonable?