LONDON (Reuters) - British Prime Minister David Cameron is committed to governing as part of a two-party coalition until the next national election in 2015, his spokesman said on Tuesday, days after Cameron raised the prospect of the alliance breaking apart. Cameron has ruled with the Liberal Democrats, his junior coalition partner, since 2010, but the two have taken increasingly different positions on issues such as Britain's role in Europe and Cameron on Sunday for the first time raised the possibility that the coalition might not last until 2015. ...