The S&P 500 (SPX) is caged between the 20-day and 50-day SMA to start Friday's trading day, says Kevin Green. He explains why the price action is significant to the index and why 7,500 is becoming the S&P's "line in the sand." He also turns to the latest moves in crude oil prices and adds his perspective to the Bank of Japan's "dovish" interest rate hike just after the Fed hiked rates in the U.S.