Propagate missing token count which differs for HRO only
This fix the previous merge request (!433 (merged)) where the configured value was not passed from hro-cloud/grid.nix to lib/issuer.nix!
The result is already live on HRO payment server: --tokens-per-voucher 150000 has been append to the parameters passed to zkapissuer service.
And it has fixed the problem: vouchers can be redeemed because now both the client and the server agrees on the same predefined value.
This should close #148 (closed) for good.
Edited by Benoit Donneaux
