Some terms missing prefixing

[mark-dce]

Please review https://github.com/curationexperts/tufts_models/blob/master/app/models/datastreams/tufts_dc_detailed.rb and make sure that all terms have an explicit namespace prefix defined

• [ ] Make an explicit prefix dc which is http://purl.org/dc/elements/1.1/
• [ ] Remove the default namespace
• [ ] update all terms that don't have a prefix
• [ ] add a method that adds the prefix namespace declaration if it's not present (like this: https://github.com/curationexperts/tufts_models/blob/master/app/models/datastreams/dca_admin.rb#L40-62)

[bmaddy]

Also:

• [x] go through and remove any attributes we don't think we're using

[bmaddy]

It turned out all our used attributes already had prefixes. The attributes in datastreams that didn't have prefixes were removed.