Add some d3Service "factory" and empty RadialGraph "directive".

I've taken the d3Service from
http://www.ng-newsletter.com/posts/d3-on-angular.html
https://github.com/EpiphanyMachine/d3AngularIntegration

I am not sure if this is the correct way to use angular.

There are also some other changes like the adding of
styles/radial_graph.css and removing of the green/red round div-things from the
subjects.html