collection and collection_name are now multiValued
Remove url to images and add reference_image_md5
add url_item back in, this is local url for obj
Add extent dcterm
Make collection and collection name required.

These are filled in during the harvesting process from the registry, so
they should be available for ALL items, every item is in a collection.
Maybe not campus or repository....
Merge pull request #1 from mredar/master

Schema changes - require collection, add extent, change name of image ref