add a system property for the configuration

- java system property 'carneades.configuration' is lookup, if its
  defined it contains the path to the .carneades.clj file
- this allow more flexibility when using Carneades with Tomcat
and allow to not bind the .carneades.clj file to the $HOME directory
- if the property is not defined, $PWD/config/carneades.clj is lookup
and then $HOME/.carneades.clj
Merge remote-tracking branch 'refs/remotes/origin/master'