Scala.js and native support

[julienrf]

Lots of our most depended on libraries (e.g. scalacheck) support Scala.js or Scala native. We should support these runtimes.

[SethTisue]

maybe we could find a volunteer or two to assist with this

[SethTisue]

@sjrd did the Scala.js part in #20

[SethTisue]

I asked for a Scala Native volunteer: https://gitter.im/scala-native/scala-native?at=5aed7e8997e5506e049c3dc7

[MasseGuillaume]

#45

[ekrich]

Complete for Scala Native - #239