Since I don't want to build another right now, drop it.

So optimistic...

Parse the byte string pass-value into an integer when initializing the server plugin

Consider lease state (expired or not) when the client computes the price of a mutable write

Require the Tahoe-LAFS API authorization token to access the ZKAPAuthorizer HTTP API.

The entire ZKAPAuthorizer client resource hierarchy is now protected by this
token, ensuring any callers at least have local filesystem access to the
Tahoe-LAFS node.

Report "Parsing redeem response failed" better

it's unclear what a good testing strategy for this logging is.  should switch
to eliot soon.

Add more logging for spending decicions