'Returns a boolean of whether this is an app that degrades
gracefully offline (i.e., is a packaged app or has an
`appcache_path` defined in its manifest).'

def guess_is_offline(self):

    if self.is_packaged:
        return True
    elif (self.latest_version and self.latest_version.all_files):
        manifest = self.get_manifest_json(file_obj=self.latest_version.all_files[0])
        return bool((manifest and ('appcache_path' in manifest)))
    else:
        return False
