Made the "DEMOBOO_FILE" field of the DEMOBOO (SBI) submission optional. (I.e. it's optional to upload a file for a book.)
Made the "DEMOBOO_FILE" field of the DEMOBOO (SBI) submission optional.
(I.e. it's optional to upload a file for a book.)

inveniosoftware/invenio,tiborsimko/invenio,tiborsimko/invenio,inveniosoftware/invenio