Bloomberg: Now that the U.S. government has cleared the Keystone XL project of any dire environmental impact, attention is returning to why the pipeline was needed in the first place: to get more Canadian oil to U.S. refineries. TransCanada Corp. (TRP)s Keystone promises to ease a bottleneck thats limited how much Canadian crude can flow south. The lack of transportation has created a glut that deflated prices for producers in the country. After five years waiting for U.S. approval, though, the need for...