WASHINGTON (Reuters) - President Barack Obama said on Friday he felt compelled to weigh in on a California same-sex marriage case before the Supreme Court because of his and society's "profoundly positive" evolution on gay rights. Obama's administration on Thursday filed a brief urging the court to allow same-sex marriages to resume in California, which banned them in a 2008 voter-approved measure known as Proposition 8. Obama did not have to submit an opinion on the case and the court's nine justices are under no obligation to give it weight. ...