Added from_json to models.
Added from_json to models.

0xfoo/flask-todolist,rtzll/flask-todolist,polyfunc/flask-todolist,rtzll/flask-todolist,polyfunc/flask-todolist,rtzll/flask-todolist,polyfunc/flask-todolist,guillaumededrie/flask-todolist,guillaumededrie/flask-todolist,0xfoo/flask-todolist,rtzll/flask-todolist,0xfoo/flask-todolist,guillaumededrie/flask-todolist