hackage-packages.nix: update Haskell package set

This update was generated by hackage2nix v20150922-6-g5d5ccfe using the following inputs:

  - Nixpkgs: https://github.com/NixOS/nixpkgs/commit/eaa43c65b3dbe002880d1c823e636b471c9b70f3
  - Hackage: https://github.com/commercialhaskell/all-cabal-hashes/commit/c048a402d3e71ab8d3af72799f148923d21ce661
  - LTS Haskell: https://github.com/fpco/lts-haskell/commit/c7012a704b558556ca067861eb156f9916aa2afb
  - Stackage Nightly: https://github.com/fpco/stackage-nightly/commit/a74568b5547db646674ce2771943ccba35e34129