Sets the data on the graph visualization from the fragment identifier. See https://github.com/curran/screencasts/blob/gh-pages/navigation/examples/code/snapshot11/main.js
function navigate(){
    if(location.hash){
      var newState = JSON.parse(location.hash.substr(1));
      if(JSON.stringify(newState) !== JSON.stringify(forceDirectedGraph.state)){
        forceDirectedGraph.state = newState;
      }
    }
  }