Add License term to ETDs

[shanitajohn]

ACCEPTANCE CRITERIA

• [x] When I look at the label for the field it should read "License" (Hyrax default)
• [x] Attribute name is license (Hyrax default)
• [x] Predicate should be inherited from Hyrax basic metadata ::RDF::Vocab::DC.rights (via Hyrax::BasicMetadata)
• [x] The data type is a string - [ ] I should be able to add more than one license - [ ] I should be able to remove a license I have added
• [x] Use CC licensing (& review existing Hyrax implementation licensing & rights) - check whether license should really be multiple
• [x] When I look at the search results page I should not see a license for each ETD
• [x] I should be able to facet on license
• [x] When I look at the .ttl view I should be able to find the license

SPREADSHEET https://docs.google.com/spreadsheets/d/1HZpXyVM8xaZZ9mE2uzsbUmWKbCd6NYJTESOrpQeMa18/edit#gid=0

[no-reply]

Licenses are single valued by default. I think we should keep that in place.