*8859* Improve article copyright/license affixing

PR for testing and comment; Do not merge.
Ah -- hence the fallback code in _getDefaultLicenseFieldValue. Sorry, I missed that detail.

That clears up my last concerns here -- when do you expect to hear back from your publishers? I'd like to sneak this into the translation round for OJS 2.4.5, which has just begun. I'd say we have a few days of grace before we risk the translation change not getting included. I haven't tested this yet, but would do so before merging.