[test] don't leave NULL columns around when making an attribute required
It doesn't matter on sqlite (it doesn't do ALTER COLUMN), but when
running this test on postgresql it fails to add the 'NOT NULL'
constraint otherwise.
/* sortable tables */
table.listing tr .headerSortUp {
background-image: url(asc.gif);
}
table.listing tr .headerSortDown {
background-image: url(desc.gif);
}
table.listing tr .headerSortDown, table.listing tr .headerSortUp {
background-color: %(listingBorderColor)s;
background-repeat: no-repeat;
background-position: center right;
}