Adding Mover base class
RDFDatastreamMover
Moves terms from an RDF datstream to attributes on the object
Support uniform interface

Let the datastream tell us if it’s versionable, but we can override
that if we want to.  This way, the interface is more uniform across the
different movers.
Use ExampleModel; optionally convert datastreams

All the models used for testing are now under their own module under
spec/support. You can now pass an option to convert RDF datastreams to
attributes on the model.