update saving files update

[paulirish]

could I have the code examples on http://updates.html5rocks.com/2011/08/Saving-generated-files-on-the-client-side updated to match the new Blob API?
you can just copy and paste from the updated examples on http://eligrey.com/blog/post/saving-generated-files-on-the-client-side
[19:37:23] oh and also apply s/BlobBuilder/Blob/ throughout the post

cc @eligrey