Conditional loading of MySQLdb module

Not all users have have the MySQL module, so moved the import to the
mysql import section. This way it's only loaded if it is needed.

And cleaned the loading of modules slightly.
Changed behaviour of settings

Now users can create an own config.cfg, which will overwrite the
settings of config-org.cfg. By adding config.cfg to the .gitignore the
file will be preserved during a update with git.