Logging guide

• We are using java.util.logging package for logging.
• The LogsCenter class is used to manage the logging levels and logging destinations.
• The Logger for a class can be obtained using LogsCenter.getLogger(Class) which will log messages according to the specified logging level.
• Log messages are output through the console and to a .log file.
• The output logging level can be controlled using the logLevel setting in the configuration file (See the Configuration guide section).
• When choosing a level for a log message, follow the conventions given in [se-edu/guides] Java: Logging conventions.