initial idea for how using tags will look

/cc @ianstormtaylor this is working, using the new tags dsl idea

it would get cleaned up / simplified more once we can remove `.load` entirely (after we merge the other 2 prs)
for this one i think we should use https://github.com/segmentio/use-https/blob/master/index.js which keeps it working in chrome extensions. maybe something like this:

```js
var tag = https() ? 'https' : 'http';
this.load(tag, this.ready);
```

although actually, i'd be down to just use `https` all the time if that doesn't break the tests, because why not really..