Configuration Change: make field_access_terms a required field.

[bseeger]

Implement resolution from: #115, which is to make the field required and therefore some value needs to be set at all times. The user only will be shown terms that are applied to them as a user, so there's no change there. They will be allowed to edit the field. The only change is that we make sure the field can never be set to -None-. In a quick look at this, I found the option of -None- goes away when the field is made to be required.

So the work is to change the field_access_term on the content types and media types to make them required fields.
Probably will need to add a term in the Islandora Access vocabulary in the snapshot to make sure there's one available in the development environment. (ultimately this will be populated and maintained by a Global Admin on a production server).

[bseeger]

Resolved with: Address field_access_terms tickets and a few minor things #178