NEW ORLEANS — BP allayed last-minute government fears of making the disaster worse and began testing the new, tighter-fitting cap Wednesday that could finally choke off the oil leak in the Gulf of Mexico. Retired Coast Guard Adm. Thad Allen, the Obama administration's point man on the disaster, said the government gave the go-ahead after carefully reviewing the risks. "What we didn't want to do is compound that problem by making an irreversible mistake," he said at the end of a 24-hour roller-coaster of hopes raised, hopes dashed and hopes raised again along the Gulf Coast. The cap - a...