LONDON (Reuters) - Still famous as the in-again/out-again member of chart-topping boyband Take That, British singer Robbie Williams says it is time to get serious as a solo artist and prove his place at the top of the pop pile. Williams told reporters on Monday he planned a 15-date European stadium tour kicking off in Manchester on June 19, 2013 and concluding in Tallinn, Estonia on August 20. "I'm buzzing. I'm ready to go. I haven't done a tour of this size since 2006," he said in London. ...