Extraction order does not need to equal insertion order.

Turns out, it did already.  Make the use order explicit in the model, anyway.

Add a web interface for retrieving the number of unblinded tokens remaining.

Unblinded tokens have a one-to-one correspondence with ZKAPs.  That is, the number of ZKAPs
remaining is equal to the number of unblinded tokens remaining.  ZKAPs are created at the point
of use, though, so they cannot be counted/listed/exported/etc directly.

Thanks, Hypothesis.

Probably useful for implementation later.
Useful for test suite right now.

Helpful for the tests

eg: nix-build --arg trialArgs '["-x"]'

using the wrong words to describe everything.

Fixes for problems arising in integration testing.

Remove unnecessary overrides

not sure this fixes anything but it might fix the PrivateStorageio build which
finds autobahn 19.1.1 instead of autobahn 19.8.1.

I think it is abstractly "more correct" too, maybe, if you can convince
yourself there is such a thing.

So we don't have to override them to get a new version anymore.  Also,
upstream has done a better job of integrating them into the overall system
than we have (with respect to other upstream changes).

Servers require and clients supply passes correctly for renew_lease.

Check the number of passes in add_lease.

This helps the client a lot with lease operations