Sync some metadata between XML and OJS backend

[jalperin]

When an XML file is the Main Manuscript file (this would need to be established somehow if there are more than one), then the metadata in the XML should be sync'ed with what's in the OJS back end (title, authors, etc.). This should probably be a two-way sync.

[asmecher]

See also the https://github.com/asmecher/oaiJats repo, where selected metadata in the XML is overridden by OJS metadata.