Oaiharvest : remove_duplicate function did not build responseDate and request tag in the new structure harvest file

[chokribr]

on 1.2 and legacy branch remove_duplicate function did not build responseDate and request tag on the new structure harvest file which will affect the value of subfield u,9,h,m in tag 035 which will remain empty when uploading the harvest record. by adding responseDate = etree.SubElement(newroot, 'responseDate') and request etree.SubElement(newroot, 'request') here https://github.com/inveniosoftware/invenio/blob/legacy/modules/oaiharvest/lib/oai_harvest_utils.py#L150