Fix broken image path in graph app.

git-svn-id: http://blockly.googlecode.com/svn/trunk@654 c400ca83-b69d-9dd7-9705-49c6b8615e23
Translate Turtle Graphics, Plane, and Graph apps to Vietnamese.

git-svn-id: http://blockly.googlecode.com/svn/trunk@655 c400ca83-b69d-9dd7-9705-49c6b8615e23