Squashed 'ext/ucamlib/' changes from 682f60b..29e39d1

29e39d1 Made the library compile for OCaml 4.02.1
e617c9f Updated the shell command execution function.
3c42942 Removed |> operator. Now part of Ocaml standard.

git-subtree-dir: ext/ucamlib
git-subtree-split: 29e39d1d8112cf3d626bf79452b006f01e8ccf3a
Updated ucamlib