Added tests for Future.

This includes:
  - Monad laws
  - Regression tests for #312
  - Extracted some tools from ActorTest that
    are useful for testing scalaz-concurrency
introduce the fproduct operation on Functor
Merge branch 'scalaz-seven' of github.com:scalaz/scalaz into scalaz-seven
rename `fproduce` (typo) to `fproduct`