Compiled with Scalaz 7.0.2

I compiled the plugin with Scalaz 7.0.2 and things [seems to be working](http://bit.ly/15mK3WQ).

However I am not sure that my changes reflect the best Scalaz practices:

 - using `toList` every time `sequence` is needed (to get the proper implicits that are not accessible with `Seq`)

 - defining `io[T](t: => T): IO[T] = scalaz.effect.IO(t)`. There is maybe such an existing function in Scalaz7?