Update to MAPv4 public draft

This should be in line with the draft at: https://docs.google.com/document/d/1Jh8ULpw0jb8kyxV-Ygw9U0n-XqXkM6_V3jxfmnkebqo/edit#
It will. I think that's reflected in the serialization I've floated here: https://gist.github.com/no-reply/f425057a660ae910a239

Note that this is a change in the MAPv4 draft, and also reflects the formal range of edm:dataProvider: http://europeana.ontotext.com/resource/edm/dataProvider