ROME/HELSINKI (Reuters) - At least half of euro zone governments as well as banks and large companies are making contingency plans in case Greece decides to leave the single currency area, even though the preferred option is still for Athens to keep the euro. Italy's Deputy Economy Minister Vittorio Grilli said his country was ready for such a possibility, if Greek voters on June 17 give power to parties that reject reforms agreed with the EU and IMF in exchange for emergency loans. ...