add class LoggerFactory with internal class LoggerConfig and
InternalLogger;change the modifiers of SimpleLogger's fields to
protected
change modifier of method println to protected
correct the classpath of eclipse project
add class Utils
add static modifier to the methods of Utils
add string tool methods for class Utils
use loglevel verbose in methods of class Utils
fix bug that didn't print throwable message in newline after log message
LoggerFactory now can parse config properties file and save the parse
results in an internal Map