Make the API flexible to conform both with Accept interface (like net.connect pattern) and HandlerFunc (like http pattern)

[daviddias]

//cc @mafintosh

• Have dialStream always return the stream obj and buffer the writes until it is ready.
• Call the callback with (err, stream) when the stream is ready.

Thanks for bringing this up :)

[daviddias]

@mafintosh updated the spec, tests and spdy-stream-muxer and multiplex-stream-muxer, let me know if I managed to get what you were looking for, right :)

[mafintosh]

@diasdavid this is perfect! thanks