adding sequencef to foldable, sequence specialized on free
fixing syntax.sequenceF_ to use Liskov instead of Leibniz as per Kenji's suggestion
Merge branch 'scalaz-seven' of https://github.com/scalaz/scalaz into scalaz-seven_sequencef
fixing a missing line, I'm learning about check-gen-type-classes!
Merge pull request #658 from vmarquez/scalaz-seven_sequencef

adding sequencef to foldable, sequence specialized on free