Updated to use OrcidProfile.orcidIdentifier throughout, instead of
relying on fallback in OrcidProfile.orcid.
Changed so that OrcidProfile.orcid does not fallback to
OrcidProfile.orcidIdentifier (because was causing <orcid> element
wrongly to appear in newer API versions).
Merge pull request #826 from ORCID/ensureRemovalOrcidElementForLaterApiVersions

Updated to use OrcidProfile.orcidIdentifier throughout