req.abort does not emit 'close'

[ostollmann]

Calling req.abort() does not emit close which is the behavior of Nodejs's http: https://nodejs.org/api/http.html#http_request_destroy_error

Related to #26, but not a duplicate I think since this isn't about the request still living, but rather about the client being able to notice that from his point of view it has been closed.

My use-case is that I catch an error, then want to call req.abort() and handle the error on 'close'.