Home prices rose slightly at 0.2 percent in August, slower than the 0.6 percent rise in July, according to the S&P/Case-Shiller 20-city composite index released Tuesday. However, data through August 2014, released this week in the S&P/Case-Shiller Home Price Indices, continue to show a deceleration in home price gains. The 10-City Composite gained 5.5 percent year-over-year and the 20-City 5.6 …