arcanist: 20140717 -> 20140812

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Regenerate with cabal2nix
haskell-wai-extra: update to 3.0.2
haskell-streaming-commons: update to 0.1.4.2
haskell-warp: update to 3.0.0.8