Bitcoin Prices Spike Above $900 But Turbulence Remains     Bitcoin prices passed $900 today, though this feat was diminished by several rallies that ultimately failed to push its value above this benchmark. Overall, the digital currency rose to as much as $904.76, after falling below $880 earlier in the session, climbing above this level amid modest volatility. Later in the session, the price mounted another comeback, hitting a high just above $905, according to the CoinDesk USD Bitcoin Price Index…