Update to readable-stream ^4.1.0

[Tiberriver256]

Hey, thanks for the contribution opportunity on this!

I got tests passing locally but I'm unsure on a couple of things:

1. Is the fact that the data object emitted by the data event a string now instead of a Buffer a breaking change? Looking at the nodejs docs for stream it looks like back to v8 it could be a <Buffer | string | any> so I'm unsure if I should do something to change it back to Buffer in the one test case or if flipping it from Buffer.concat to Array.prototype.join is good enough.
2. I was unsure if you wanted me to change the version in the package.json file or if you did that yourself.

Thanks again!

Fixes: #5

[mafintosh]

Awesome, thanks! If you want to, then this can be implemented using the new _final hook in streams,

stdout-stream/index.js

Lines 46 to 50 in 23b5fde

	s.on('finish', function() {
	fs.close(1, function(err) {
	if (err) s.emit('error', err);
	});
	});

If not we can leave it as is also :)

[mafintosh]

1. no issue, this is only a writable stream
2. you did it the correct way - always easier if the maintainer does that.

[Tiberriver256]

Awesome, thanks! If you want to, then this can be implemented using the new _final hook in streams,

stdout-stream/index.js

Lines 46 to 50 in 23b5fde

	s.on('finish', function() {
	fs.close(1, function(err) {
	if (err) s.emit('error', err);
	});
	});

If not we can leave it as is also :)

I attempted this but things weren't as straightforward as I was hoping. I think it might be best to leave it as-is.

[mafintosh]

np, i'll fix that for you.

[mafintosh]

2.0.0 - using the _final hook now also