publication_date field not auto-populated for new record versions

[cc-a]

Creating a new version for a published record is currently not possible because we have hidden the publication_date field. This field is not auto-populated when creating a new record. The publication_date from the previous version is not populated into the form. The relevant logic appears to be here.

[richard-jones]

See also #121

[cc-a]

This should be resolved by #167 but would like a test before this is closed.