Build clean up now that we are only building for scala 2.11.x

* Simpler crossMapped
* Removed scalaz6
* Just use latest versions of specs2, scalatest and scalaz
Merge pull request #1611 from lift/diego_build_cleanup

Build clean up now that we are only building for scala 2.11.x

 - Simpler crossMapped
 - Removed scalaz6
 - Just use latest versions of specs2, scalatest and scalaz