SHANGHAI (Reuters) - Tesla Inc plans to start work on a new plant in Shanghai as soon as next month as part of a plan to more than double production capacity in China to meet growing demand for its cars in the country and export markets, two people familiar with the matter told Reuters. Once the new plant is fully operational, Tesla will have the capacity to produce up to 2 million cars per year at its expanded Shanghai facility, the company's main export hub, according to the people, who asked not to be identified in discussing still-private plans. The...