Add log severity and console color based on severity

[ldilley]

Add a 2nd parameter to Util.Log() for severity. Use a switch statement to modify Console.ForegroundColor based on the passed severity level (ConsoleColor.Red for exceptions, errors, and critical messages, ConsoleColor.Yellow for warnings, ConsoleColor.White for informational messages, and ConsoleColor.DarkGray for trace, debug, and verbose messages).