update baxter.l generation and model

- add baxter.l since baxter_simple.urdf is not released yet
- add code to use baxter_simple.urdf

![screenshot from 2014-10-31 11 48 04](https://cloud.githubusercontent.com/assets/493276/4866874/10d4cace-6130-11e4-9b2d-aedcb8c2ed9e.png)