Minor change walkway item rendering

This picture is before fixed item render on the ground. That too big.
![2557-09-13_20 38 36](https://cloud.githubusercontent.com/assets/6128413/4263418/26162610-3be4-11e4-81bc-fefe2fadffec.png)

And this I will make it to better rendering.
![2557-09-13_20 42 46](https://cloud.githubusercontent.com/assets/6128413/4263420/3539b1ac-3be4-11e4-80f4-37a9fcfdb814.png)