Migration to Vertx 3

* Removal of mod building
* Bump vertx version
* Removal of vertx maven plugin
I have not seen any vertx-maven-plugin for 3.x. They are using a custom solution to run examples. I can only assume that the vertx maven plugin will be updated once they added a way to run verticles written in .js outside of the classpath. (which is afaik currently not possible)