LP#1305958 Fix copy table header ID error

Currently there is a <td headers='copy_header_date_format'> entry in
copy_table.tt2 that does not link to an associated table header with an
ID of that value. The desired target ID is "copy_header_create_date".

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Signed-off-by: Dan Wells <dbw2@calvin.edu>