Fix bug trying to concatenate list to string #186

    def get_scope(self):
        """Return list with needed access scope"""
        return (self.DEFAULT_SCOPE or []) + \
               self.setting('SCOPE', [])

When the user has a 'SCOPE' set part after + is a string. That in turn
tries to do:

[] + ''

That isn't valid python and throws an error, this fixes that.