Test runner

Why do I get a ClassCastException during the test (see below), even though `ScalaVerticleFactory` extends `org.vertx.platform.VerticleFactory`? If someone could check out this code and help me getting rid of that, we'd have a working ScalaClassRunner with access to the scala.Verticle things... ;)

Sorry for that many commits, but the test relies on the complete-api branch I posted for review earlier.

    org.vertx.scala.tests.core.http.ScalaHttpTest > testCreateServer FAILED
        org.vertx.java.platform.PlatformManagerException: Failed to instantiate verticle factory
    
            Caused by:
            java.lang.ClassCastException: org.vertx.scala.platform.impl.ScalaVerticleFactory cannot be cast to org.vertx.java.platform.VerticleFactory