[ADD] URL shortener

TASK : https://www.odoo.com/web#id=8277&view_type=form&model=project.task&menu_id=3942&action=327
![capture d ecran 2014-12-10 a 15 52 26](https://cloud.githubusercontent.com/assets/3533550/5377667/9737fb40-8084-11e4-810f-ca983e20ee7e.png)