resolves #38 replace close option by destroy

[ggrossetie]

Not sure how to test but close is not a valid option: https://nodejs.org/api/stream.html#new-streamreadableoptions

resolves #38

[ggrossetie]

I don't know how to add a unit test without exporting the socket object (i.e., public accessor) to make sure that the socket was destroyed when the writable stream is closed.

Alternatively, I can add a new option onSocketDestroyed (callback function) called after socket.destroy?

Thoughts?

[mcollina]

Export the socket.

[ggrossetie]

Unit test added!