hackage-packages.nix: update Haskell package set

This update was generated by hackage2nix v20151217-10-ga610b1b using the following inputs:

  - Nixpkgs: https://github.com/NixOS/nixpkgs/commit/94492ca8484ac1cc1962d42050ff6cdc145665f6
  - Hackage: https://github.com/commercialhaskell/all-cabal-hashes/commit/b3a9ab4a6048a52dbabe68389d8edc10062ee925
  - LTS Haskell: https://github.com/fpco/lts-haskell/commit/e7c362999942041130d6f66c30289bd6be0430a3
  - Stackage Nightly: https://github.com/fpco/stackage-nightly/commit/b98e7e2d4fc1c47179a362d16d98290990eb8c28