Adapt taverna-wfbundle to use taverna-robundle

We should get rid of the outdated taverna-scufl2-ucfpackage and taverna-scufl2-wfbundle should instead use taverna-robundle for storing and managing a wfbundle.

This changes API several places, e.g. WorkflowBundle.getResources() - and bundle paths should be returned as java.nio.file.Path instances rather than Strings.

The experimental branch https://github.com/apache/incubator-taverna-language/tree/ucfpackage-robundle goes somewhat along the way - and includes a transitionary UCFPackage
https://github.com/apache/incubator-taverna-language/blob/ucfpackage-robundle/taverna-scufl2-ucfpackage/src/main/java/org/apache/taverna/scufl2/ucfpackage/UCFPackage.java
that proxies through to Bundle from taverna-robundle.

I think for backwards compatibility we should still save the ODF Manifest - the support for this is already in robundle: