'Reloads display applications: by id, or all if no ids provided
Returns tuple( [reloaded_ids], [failed_ids] )'

def reload_display_applications(self, display_application_ids=None):

    if (not display_application_ids):
        display_application_ids = self.display_applications.keys()
    elif (not isinstance(display_application_ids, list)):
        display_application_ids = [display_application_ids]
    reloaded = []
    failed = []
    for display_application_id in display_application_ids:
        try:
            self.display_applications[display_application_id].reload()
            reloaded.append(display_application_id)
        except Exception as e:
            self.log.debug('Requested    to    reload    display    application    "%s",    but    failed:    %s.', display_application_id, e)
            failed.append(display_application_id)
    return (reloaded, failed)
