streams: introduce StreamWrap and JSStream

streams: introduce StreamWrap and JSStream

Introduce a way to wrap plain-js `stream.Duplex` streams into C++
StreamBase's child class. With such method at hand it is now possible to
pass `stream.Duplex` instance as a `socket` parameter to
`tls.connect()`.

PR-URL: https://github.com/iojs/io.js/pull/926
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>