Update OAI_GETRECORD_XML model

- Add "ak:rel" to all dc tags
Fix enrich_location

- Update def get_isostate to append empty string to iso_arr and
  state_arr in the case where there was no iso/state match.
- Update def create_dictionaries to create name/iso field only if
  the name/iso value is not empty/exists.
Merge branch 'develop' into virginia