Remove owl:sameAs from NIDM-Exp ontology

[khelm]

Remove the owl:sameAs from prov:collection and prov:plan. Use the prov terms, but placed in the graph where the sio versions would normally be placed.

[khelm]

This is done, but there is a complication with the term prov:Plan. The issue is that it really should be a child term of the SIO term sio:SIO_000091 (action specification), but properly placing it there in the graph means that I would have to modify the prov-o file so that the subclassOf statement of prov:Plan was removed. I can do this since I'm currently using a local import of prov-o, but can't do this in general once we switch back to using the online version. So, for now, prov:Plan will have to stay in two places in the graph.