oairepository: date overflow fix
oairepository: date overflow fix

* Fixes issue with max date overflow when in e.g. US timezones.

Signed-off-by: Lars Holm Nielsen <7eaffca9f7cd98839b5821d0d23e09ff764b82cd@cern.ch>

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