Graph interface additions, .v and .e fixes

 * added newTransaction, shutdown, addVertex, addEdge
 * fixed .v and .e and made them behave similar to their groovy brothers

Example for .v:

	g.v(24012, function (err, v) {
	  console.log(v.getPropertySync('user_id'));
	});

	g.v([24012, 12860], function (err, pipe) {
	  pipe.toJSON(function (err, data) {
	    console.log(data);
	  });
	});

Sorry for breaking .v and .e - I had clearly never tested them appropriately.