Log Message:
Update to 0.3.1

CHANGELOG:
0.3.1
  - Minor documentation fix
0.3
  - Added instances for Control.Applicative.Backwards and
	Data.Functor.Reverse from transformers 0.3, taking them from
	transformers-compat if necessary for transformers 0.2
0.2.2
  - allow compatibility with the platform; transformers
0.2.1
  - dep bump; transformers