SCARBOROUGH, Tobago (Reuters) -Nine days after a slick was first spotted by Trinidad and Tobago's Coast Guard, an oil leak from a capsized barge remains unplugged, according to first responders and authorities, raising alarms for nations across the Caribbean Sea. The spill has spread miles from Tobago's shore, the area first impacted by the incident, leading authorities to alert its Caribbean neighbors, including Venezuela and the island of Grenada. A barge pulled by a tugboat caused the spill, Trinidad's government has said, but details of the incident remain unclear, includi...