Fix #SL288

Fix #SL 288 -> http://bugs.sugarlabs.org/ticket/288
"icon for mime-type text/x-python"

![captura de pantalla - 211113 - 16 40 33](https://f.cloud.github.com/assets/2650479/1594544/be1447ea-52dc-11e3-8e20-68ec82b357b5.png)
![captura de pantalla - 211113 - 16 38 31](https://f.cloud.github.com/assets/2650479/1594547/c533a340-52dc-11e3-964f-e13d3e728b51.png)
![captura de pantalla - 211113 - 16 39 41](https://f.cloud.github.com/assets/2650479/1594549/c981cfe4-52dc-11e3-9c45-3d881324d067.png)