Delete the Haskell contrib package.
Review Request #3631 - Created March 31, 2016 and submitted
|benjyw, jsirois, mateor, stuhood, zundel|
Right now its tests are too flakey due to stack bootstrapping issues. This should be easy to revert when the upstream stack issues are resolved or worked around.
CI is baking: https://travis-ci.org/pantsbuild/pants/builds/119914761