Implement a haskell-suite compiler support

Haskell suite adds a new compiler flavor to Cabal, except it is not tied to any particular compiler. Hopefully, this may be one of the last compiler flavors added to Cabal. (related: https://github.com/haskell/cabal/issues/57)

It is already used by the haskell suite interface generator.
(See http://documentup.com/haskell-suite/haskell-names#module-interfaces/generating-interfaces)

As far as I know, Fay is also interested in using haskell-packages, but the necessity to build a patched version of Cabal is a major hindrance for them.