Registers declared addon's

def _add_addon_views(self):
        """
            Registers declared addon's
        """
        for addon in self._addon_managers:
            addon_class = dynamic_class_import(addon)
            if addon_class:
                # Instantiate manager with appbuilder (self)
                addon_class = addon_class(self)
                try:
                    addon_class.pre_process()
                    addon_class.register_views()
                    addon_class.post_process()
                    self.addon_managers[addon] = addon_class
                    log.info(LOGMSG_INF_FAB_ADDON_ADDED.format(str(addon)))
                except Exception as e:
                    log.exception(e)
                    log.error(LOGMSG_ERR_FAB_ADDON_PROCESS.format(addon, e))