By Mike Collett-White and Yasmine Saleh CAIRO (Reuters) - Egypt's political transition after President Mohamed Mursi was ousted by the military stumbled at the first hurdle, after the choice of liberal politician Mohamed ElBaradei as interim prime minister was thrown into doubt by Islamist objections. ElBaradei's nomination had been confirmed by several sources and state media on Saturday, but just before midnight a presidential spokesman told reporters that the prime minister had not in fact been chosen. ...