src/lib/dhcpsrv/csv_lease_file4.cc
    CSVLeaseFile4::next() - modified to produce a read error
    if the hardware address is empty and the lease state
    is NOT declined.

    CSVLeaseFile4::readHWAddr() - no longer throws an exception
    if the hardware address is empty

src/lib/dhcpsrv/tests/csv_lease_file4_unittest.cc
src/lib/dhcpsrv/tests/lease_file_loader_unittest.cc
    Changed test lease data so invalid records do not
    have lease state of declined