I know some of this code might change later but for now let's re-use the notes dict which is [created here](https://github.com/mozilla/webpay/blob/master/webpay/pay/views.py#L110-L111). This will benefit us in a few ways:

* notes get saved to the transaction object (helpful for persistence and auditing)
* notes get deleted after getting stored which cuts down on session cookie size and helps prevent synchronization issues
* lots of code is around to help pass around notes so it should fall into place

So something like:

    notes = sess.get('notes', {})
    notes['network'] = {}
    ...
    sess['notes'] = notes