custom metadata blocks now loosely require properties files as well

[donsizemore]

Gustavo would like to test against https://github.com/IQSS/dataverse.harvard.edu/files/8962263/customSAEF_TSV_and_properties_files.zip

update: by "loosely" I'll quote Leonid: these .properties files are not really needed at all on a default/single language installation

For now, as an “incremental” solution, I’ll be telling people (and myself, for our prod.) - ignore the .properties; you don’t need them; either live with the logging noise, or lower the log level.