hackage-packages.nix: update Haskell package set

This update was generated by hackage2nix v20150922-16-g255fd25 using the following inputs:

  - Nixpkgs: https://github.com/NixOS/nixpkgs/commit/413771bf48d51a08990f936fa2b102fef6034bd4
  - Hackage: https://github.com/commercialhaskell/all-cabal-hashes/commit/34485133f3a0653136d63b49afa2e3269b5f64d1
  - LTS Haskell: https://github.com/fpco/lts-haskell/commit/c5f1e507cd73fda2551f36492eb1d0c3f7b65f3a
  - Stackage Nightly: https://github.com/fpco/stackage-nightly/commit/c5032276f963a5c34b1e2427d0ee7b722a078a46