Added Warp (Haskell) benchmark

Hello,

I made a Warp attempt, it works on my computer but please give it a go before merging it. There is a binary executable that should work. If it doesn't, you might have to compile it. :-)

If you have to compile it and if you are on OS X 10.9+ and if you don't have Haskell and if you use Homebrew, please let me know before installing it.

Note: I'm not a Haskell pro and there might be better ways to solve this problem.