|#98 Convert wrapper classes to AnyVal, use `asJava` to get Java POJO

* All wrappers except Message, RouteMatcher and Vertx have been
converted to AnyVal instances.
* AnyVal instances don't allow `this.type` to be referenced, so
instead a Self type was created with a covariant type parameter
that points to itself.
* Wrap class has been merged with Self, since both are very
tighly related. Self defines the return type and wraps it using
self() method. Each wrapper class defines what self() should return
* Removed all Wrapped* classes and just merged them into their
corresponding trait.
* Added missing javadoc and corrected where necessary
* Added missing copyright notices