Port environment creation from Java core

The Scala SDK provides all interfaces in native Scala, with the exception of the cluster environment building, which is in Java.

I'll port this over to provide a better Scala experience.

In addition, I need to deal with ownership of environments.  If an environment is created and owned by a cluster, then cluster.shutdown() will destroy it.  Otherwise, it is down to the user to destroy it - so it can be shared by multiple clusters.