haskell-mtl: update 2.1.x branch to version 2.1.3.1
haskell-concrete-typerep: disable test suite to avoid spurious failures

http://hydra.cryp.to/build/209703/nixlog/1/raw
haskell-hspec-checkers: re-generate expression with cabal2nix
haskell-persistent-postgresql: update to version 2.1.0.1
haskell-persistent: update to version 2.1.0.1
haskell-pipes-attoparsec: update to version 0.5.1.1