[TIMOB-8001] iOS: Can write to a BufferStream created in read-only mode

var win1 = Titanium.UI.createWindow({
	title : 'Tab 1',
	backgroundColor : '#fff'
});
win1.open();

var stream1 = Ti.Stream.createStream({
	source : Ti.createBuffer({
		value: "Now is the time for all good men to come to the aid of their country. Or party. Or something. Honestly, I don't remember."
	}),
	mode : Ti.Stream.MODE_READ
});

var stream2 = Ti.Stream.createStream({
	source : Ti.createBuffer({
                // Note that if the buffer is not initialized with a length or data, iOS throws a different exception.
		length: 100
	}),
        // Ooops! It's a read-only stream!
	mode : Ti.Stream.MODE_READ
});
var sync = true;
if(sync) {
	var bytes = Ti.Stream.writeStream(stream1, stream2, 100);
	Ti.API.info("Bytes written: " + bytes);
} else {
	Ti.Stream.writeStream(stream1, stream2, 1024, function(arg) {
		Ti.API.info("bytes processed: " + arg.bytesProcessed);
		Ti.API.info("Event: " + JSON.stringify(arg, false, 2));
	});
}