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 22 01 20](https://f.cloud.github.com/assets/151042/912869/05738f6a-fe0a-11e2-8116-d7f74f12cd64.png)