add Carneades to the nix environment and Makefile

This add Carneades to the Makefile and nix environment.

Carneades is not added to the 'all' target Makefile yet. Should it be?

To run Carneades the user must still create a configuration file in the $HOME directory, this is not done by the Makefile (as this would break Carneades configurations from developers not working only on Policy Compass).

I don't see the necessity of creating a supervisor configuration yet, as the carneades.war is copied into the tomcat webapps directory, which is itself configured by supervisor.

localhost:10005/carneades/#/projects should return a list of projects when everything is configured properly.