Not all certificates contain a 'code' element,
making this column unnecessary. It may also
confuse users when it is not applicable. For
those who are interested they can always use
the 'verify' functionality to confirm
certificates, rather than using this page.
The table is now an instance of 'table_sql', not 'html_table'.
This made sorting easy to implement, with the added benefit
of taking advantage of the spout library for exporting data.