hackage-packages.nix: update Haskell package set

This update was generated by hackage2nix v20150922-18-g676e5bd using the following inputs:

  - Nixpkgs: https://github.com/NixOS/nixpkgs/commit/0d6c2ccabfffd3942f824ac359c8e36e21d4afb6
  - Hackage: https://github.com/commercialhaskell/all-cabal-hashes/commit/4571e32cd95bf42a53c85e7c8a496d584c7b028f
  - LTS Haskell: https://github.com/fpco/lts-haskell/commit/0d493eae3616d7da684f1b6bf35709bc4408a5c0
  - Stackage Nightly: https://github.com/fpco/stackage-nightly/commit/c10e6d05feb8b1d4a9cb2ef479d2a448934b7984