TOKYO (Reuters) - Summertime commuting in Japan in high heat and humidity and huge crowds can be particularly stressful, but one train company has found a way to help its passengers relax. Customers who book a seat on Fuji Kyuko's Friday night beer run can sit back and spend a two-hour trip being served as much locally brewed beer as they can drink. The beer train plies a route near Mount Fuji, some 100 km (60 miles) southwest of Tokyo, normally used by businesspeople and students. "People are enjoying it so much, it is almost completely booked up throughout August,"...