Port to scala-js

Hi!

shapeless atop of scala-js is required to [parboiled2 port](https://github.com/alexander-myltsev/parboiled2/compare/sirthias:master...scalajs-2.11).

Now I am using bintray for public access. Would you merge it to main codebase?

Note this change:

```Scala
sources in (Compile,doc) := Seq.empty
```

scala-js will not be published successfully otherwise.