By William Mallard TOKYO (Reuters) – This week's turbulence in Tokyo markets exposes a key risk of Prime Minister Shinzo Abe's all-in strategy to revive Japan's economy – if investor confidence falters, the government and the Bank of Japan may be left with few options to turn the tide. On Friday, the Nikkei share average had another tumultuous session, traversing a 7.1 percent range between positive and negative territory before ending up 0.9 percent. The violent moves kept investors on edge after a 7. … Read more here: Market turbulence poses first serious test for Abenomics