Fold dmtf into vcloud-director (its only user).

Simplifies the build and localizes vcloud-director maintenance.
Stick with `jclouds.version` here? It generally will be the same as the parent version, but not always. From what I can see (cf. e.g. the [Abiquo POM](https://github.com/jclouds/jclouds-labs/blob/master/abiquo/pom.xml)), versions of deps from jclouds core use `jclouds.version`