Implement Vhost browsing via http and filesystem

We need a way to allow user to select a virtual host and open its URL in the browser as well as open it's document root in the filebrowser (eg. nautilus).

Browse Vhosts. mockups needed :-)

  - Toolbar button. this is very easy and shuold be implemented anyway.
         mocks:
             - http://img207.imageshack.us/img207/6948/screenshottestgladepyfb8.png
             - http://img523.imageshack.us/img523/5976/screenshottestgladepy1qb9.png
  - embed links in the vhost list, like the links in UpdateManager (this would be very cool, but less easy)
  - contextmenu for vhosts (doubtful - I wouldn't bother to do that, for now)