Convert lib/conf.rb to use XDG specification.

Conform to XDG specification standards for applicationfiles.  By default it will put files in the $XDG_DATA_HOME/clearskies directory.

In the event $XDG_DATA_HOME is not set it is defaulted to $HOME/.local/share per the specification.

See: http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html#variables