idea for loaded script/img/iframe

@ianstormtaylor initial idea for comparing the `integration.load` returned result with a string passed in. basically it's a bit complex because you convert the strings both to objects, then back again, so you can more easily compare the strings. we can work on this more definitely, but just a start. goes along with another PR in just a sec.
would be nice if we're gonna use this to pull it out into a separate module. i wonder if there are any cross browser problems with this. if not, i wonder if we can just use `node.attributes` directly?