Adds a panel group to the dashboard.

def _process_panel_group_configuration(self, config):
        """Adds a panel group to the dashboard."""
        panel_group_slug = config.get('PANEL_GROUP')
        try:
            dashboard = config.get('PANEL_GROUP_DASHBOARD')
            if not dashboard:
                LOG.warning("Skipping %s because it doesn't have "
                            "PANEL_GROUP_DASHBOARD defined.", config.__name__)
                return
            dashboard_cls = self.get_dashboard(dashboard)

            panel_group_name = config.get('PANEL_GROUP_NAME')
            if not panel_group_name:
                LOG.warning("Skipping %s because it doesn't have "
                            "PANEL_GROUP_NAME defined.", config.__name__)
                return
            # Create the panel group class
            panel_group = type(panel_group_slug,
                               (PanelGroup, ),
                               {'slug': panel_group_slug,
                                'name': panel_group_name,
                                'panels': []},)
            # Add the panel group to dashboard
            panels = list(dashboard_cls.panels)
            panels.append(panel_group)
            dashboard_cls.panels = tuple(panels)
            # Trigger the autodiscovery to completely load the new panel group
            dashboard_cls._autodiscover_complete = False
            dashboard_cls._autodiscover()
        except Exception as e:
            LOG.warning('Could not process panel group %(panel_group)s: '
                        '%(exc)s',
                        {'panel_group': panel_group_slug, 'exc': e})