Support transformers-0.4.0.0

Hi Mikhail,

It would be great if you can release this ASAP, so I can update monad-control and lifted-base.

I think we only need a minor version bump now according to the updated [PVP](http://www.haskell.org/haskellwiki/Package_versioning_policy) regarding instances. So I will let monad-control [depend](https://github.com/basvandijk/monad-control/commit/233537161fa9dd2c16b96aa4dfc88c0a640e83c3) on transformers-base-0.4.1.1.

Thanks!