hackage-packages.nix: update Haskell package set

This update was generated by hackage2nix v20150922-46-gf1bbc76 using the following inputs:

  - Nixpkgs: https://github.com/NixOS/nixpkgs/commit/f9c10dd1aa7657b55c052ff3e580f2dddb44aa0f
  - Hackage: https://github.com/commercialhaskell/all-cabal-hashes/commit/fda7f3f4778438c6f664c963c5ff12698ac5bbbc
  - LTS Haskell: https://github.com/fpco/lts-haskell/commit/57dab1c9974199e11130c3da70ffa31480a9ca37
  - Stackage Nightly: https://github.com/fpco/stackage-nightly/commit/a30c2abd607146f1b33148020d36f8198914c543