26utm_content%3Darticle%26utm_source%3Demail%26utm_medium%3D1Otoday.1105%26china_variant %3DFalse&utm_medium=10today.1105&china_variant=False> Uber, Travis Kalanick's smartphone-based car service, has been valued at $18.2 billion, but its C.E.O. still spends a lot of his time on the warpath. His enemies include th