add content type to Link model
don't assume our internal format can always track schema.org, schema.org might change we need to be back compat
initial atom results, in progress
fix indenting
ResultItem: convenience methods for ISO 639-1 and -3
fill out atom
atom results, better test coverage, including unique_id atom:id
atom results, add dcterms:publisher, fix tests that weren't being run
atom results, fix html abstract test
atom results, fix atom:id test
atom results, test_with_full_date