Added Default Logger to decouple simple log handling

This definition was extract from tesnode, and can be reused to generate a
simple log() funcional for several others tools.

erp5/util/log.py

+import logging
+
+class DefaultLogger(object):
+  logger_format = '%(asctime)s %(name)-13s: %(levelname)-8s %(message)s'
+
+  def __init__(self, id):
+    self.logger = logging.getLogger(id)
+    logging.basicConfig(level=logging.INFO,
+                        format=self.logger_format)
+
+  def __call__(self, message):
+    self.logger.info(message)
+
+  def enableConsole(self):
+    self.logger.addHandler(logging.StreamHandler())
+    self.logger.info('Activated console output.')
+
+  def enableLogFile(self, logfile):
+    formatter = logging.Formatter(self.logger_format)
+    file_handler = logging.FileHandler(filename=logfile)
+    file_handler.setFormatter(formatter)
+    self.logger.addHandler(file_handler)
+    self.logger.info('Activated logfile %r output' % logfile)
+    self.logfile = logfile
+
+  def disableLog(self):
+    self.logger.addHandler(logging.NullHandler())
+