Pause and resume don't work on a read stream

Hi! 

Thank you for your work on gridfs-stream. I found an issue while using the read-stream. When using pause(), no more data is coming from the stream. So the following code:

	readStream = gfs.createReadStream('5139c756d4efb3741200006c');

	console.log('Pausing stream');
	readStream.pause();

	setTimeout(function () {
		console.log('Resuming stream');
		readStream.resume();
	}, 1000);

	readStream.on('data', function () {
		console.log('Data');
	});
	readStream.on('end', function () {
		console.log('End');
	});

Returns ouput:

	Pausing stream
	Resuming stream

And not the expected:

	Pausing stream
	Resuming stream
	Data
	End

Any advice is greatly appreciated!

Regards,

Tim