Add contravariant laws; test them on Function1.
Contravariant instance for Kleisli.
Merge pull request #287 from S11001001/topic/contravariant

Contravariant laws; instance for Kleisli.
Use Travis CI default sbt and extend build matrix
Merge pull request #247 from gildegoma/scalaz-seven-travisci-fullmatrix

Travis CI: Extend the build matrix for Scalaz Seven branch