add a new column in the repository table
create an abstract class to have common settings among all subsystems
add some common settings#
remove message printer related classes to be replaced by Logger
create classes for logging
make AbstractSettings use the logger
make a logger for errors
add the getter for eLogger
change the format of loggers
import log4j
change logging functions from java.util to log4j
add a function to check validities of the given setting values
add setter and getter for repository retriever and registerer
add an exception class for illegal format of files
implement a function to load and register repositories from a given csv file