Placed record id logic in the select-id module.
Updated record id logic to use the URL field of the OAI-PMH handle, if any, as the _id and to save the hashed _id as the id.
Updated revision check logic to use the ingested document _id field when comparing to an existing CouchDB document id.
Updated select-id module to account for an empty data[prop] array.
Merged thumbnails_download_preview branch.
Update date enrichment logic to properly set created date
Do not put bogus date values in date start/end
Fixes for Travis and loading tests from lib directory.
Fixed travis config file.
Merge branch 'travis_fixes' of github.com:dpla/ingestion into travis_fixes