Get src/main and src/test compiling

We could add an `asJava()` method to all concrete implementations, don't you think so?

Then we could just do a `vertx.asJava()` on our Scala version of Vertx to get the Java delegate.

Do you think it's a good idea to expose `jvertx` by using `protected`? If we'd add the `asJava()` to all classes, we wouldn't really need that and users won't try to use Java versions all the time...