Overriding the common.webinterface setting can result in the user being unable to change the gui-language

If you override the common.webinterface as we do for the simple_harvest
you can end up being unable to change the gui-language to something different than the default language (English).
As it is now if you override the list of sitesections to be included in the GUI
you also need to override the list of languages available to the user.
Otherwise only english will be available!