Remove the 'urn:jboss:domain:remoting:5.0' schame and corresponding model versions.

When working on the management models we first need to check the last final release so that we can identify if we do need to increment the versions or not.

I had already added a clean version 4 ready for ongoing development.

Also on a related point it would be better if we can add the new version in one commit and then make changes in a subsequent commit - this way we can use various git tools to see the changes made otherwise the first set of changes are never visible.