Move the default config.cfg to $XDG_CONFIG_HOME

The new place for config.cfg is now
$XDG_CONFIG_HOME/easybuild/config.cfg
Moved config file: some reworks after comments
default config location is decided in get_user_easybuild_dir()
config.cfg: split line into two parts
Merge pull request #820 from wpoely86/configcfg

Move the default config.cfg to $XDG_CONFIG_HOME