code: def record_manifest(self):
          
          manifest = super(ApacheSatchel, self).record_manifest()
          manifest['available_sites'] = self.genv.available_sites
          manifest['available_sites_by_host'] = self.genv.available_sites_by_host
          manifest['media_timestamp'] = self.get_media_timestamp()
          return manifest
docs: Called after a deployment to record any data necessary to detect changes
          for a future deployment.