Doc Rivers’ “Ubuntu” mantra helped lead the Boston Celtics to its first NBA Eastern Conference championship in 20 years.    So said one ESPN commentator, citing the Beantown coach’s use of the African term as a way to drive the team’s “collective success.” The sportscaster said it following the Celts win over the Detroit Pistons Friday night to clinch a spot in the NBA finals against the LA Lakers.   Naturally, my head leapt from my laptop to TV screen upon hearing the word uttered on a sports network. (I was reading Boston.com's account of the title after the trophy ceremony).  The Celts wound up in last place last year and needed a “community” mantra for the 2007-2008 season to meld together old timers like Capt. Paul Pierce with hot scoring...