Fix #11 - Make minor/milestone version updates easier

- Remove Vert.x minor/milestone version from the cartridge metadata
- Update setup/install/control scripts
- Update README, improve Updating Vert.x steps

https://github.com/vert-x/openshift-cartridge/issues/11
https://bugzilla.redhat.com/show_bug.cgi?id=1158736
Ahh since install is not called again. So yea this sounds familiar and I think I opted with the "if you want the new config files" you can copy them over yourself" maybe ? Not sure what's the best approach here. I'd love to have dist config + user config and vertx figure it out.