add configuration file for connections

[lefred]

Let's add cfg file to deal with the connections. The file will be /etc/online-migration.cfg and its content will be like:

 [world]
 user=root
 password=fred
 host=127.0.0.1
 port=3340

 [sysbench]
 user=test
 password=test
 host=127.0.0.1
 port=3306