Update PaymentServer

* Merge pull request #79 from PrivateStorageio/78.tests-in-nix-packaging
* Merge pull request #80 from PrivateStorageio/77.payment-metadata-handling
* Merge pull request #83 from PrivateStorageio/82.currency-parsing
* Merge pull request #85 from PrivateStorageio/84.currency-and-price

nixpkgs.json

 { "name": "nixpkgs"
-, "url": "https://github.com/PrivateStorageio/nixpkgs/archive/d7c46f46c3e6acfcde44bb05877fd5c9f07dfe1b.tar.gz"
-, "sha256": "1vddxhp3ljaq9qqzbpjp2kx34ps7nzbsn4zy31x0748a52rlsh0q"
+, "url": "https://github.com/PrivateStorageio/nixpkgs/archive/e830c2bfd25926d2479f5cfb88a656a6dd9ce93a.tar.gz"
+, "sha256": "1jjslnl1v83317arafsp31jch00d4h98jv0ky0xvl7qblzb7ncvr"
 }