SPIKE: Think of ways we could be better if `pywb` was changed

Now we are on the latest version of `pywb` we have the opportunity to engage with Ilya Kreymer (the maintainer) to see if he'd be willing to advise or even implement some features that might help us out.

Hypothesis has worked with Ilya in the past and now our `pywb` isn't horribly out of date there might be an opportunity to do it again.

We should have a think about:

* Things we are working around, that we could work through instead
* Some of the blocking requirements we have, which might be of general use
* Direct proxying by certain criteria (like video content)
* Maybe adding some defined hooks to let us customise the system more easily
* Maybe adding some hooks to remove all our custom hackery