harvesting-kit: Filters empty subfields of field 773

* Empty subfields are now removed before being added to the record

Signed-off-by: Martin Vesper <martin.vesper@cern.ch>
Merge pull request #77 from mvesper/filter_field_773

harvesting-kit: Filters empty subfields of field 773
Merge pull request #78 from Dziolas/master

Elsevier: automatic update of delivery dates for packages.
Removes whitespaces from package names in db "package" table.