New Attribute: DataModel Version

[nlee-sage]

It will be important to link the annotations to the data model version. I realize the data model changes over time based on contributors suggestions. The data model will also change as Sage moves towards creating a core data model. By having a "dataModelVersion" in the provenance or as an annotation, we can trace differences in annotations. I suggest this be a feature in DCA or a part of the curation process.