Graph interface additions, .v and .e fixes

- added newTransaction, shutdown, addVertex, addEdge
- made .v and .e to behave similar to their groovy brothers

    g.v(24012, function (err, v) {
      console.log(v.getPropertySync('user_id'));
    });

    g.v([24012, 12860], function (err, pipe) {
      if (err) throw err;
      pipe.toJSON(function (err, data) {
        console.log(data);
      });
    });