By Frank Pingue (Reuters) -Tampa Bay Buccaneers quarterback Tom Brady, widely considered the greatest player in NFL history, announced his retirement on Tuesday after an age-defying career during which he won a record seven Super Bowl championships. The 44-year-old Brady spent 20 seasons with the New England Patriots, winning six Super Bowl titles, before relocating to Tampa Bay and leading the Bucs to a championship last season. “I have always believed the sport of football is an ‘all-in’ proposition – if a 100% competitive commitment isn’t there, you won’t succeed, and success is what I love…