Browser options

Add 2 options to control browser integration:
- checkbox to enable/disable this feature (it will stop listening immediatly if disabled)
- a spinbox to select default listening port (default is 8000)

![capture du 2013-08-05 15 45 31](https://f.cloud.github.com/assets/151042/910212/b75d356c-fdd5-11e2-8c9e-fc301791b426.png)