'Function downloads additional information from quay.io to
get the tag-field which includes the version number.'

def get_additional_repository_information(self, repository_string):

    url = ('%s/%s/%s' % (QUAY_API_URL, self.organization, repository_string))
    r = requests.get(url, headers={'Accept-encoding': 'gzip'}, timeout=12)
    json_decoder = json.JSONDecoder()
    decoded_request = json_decoder.decode(r.text)
    return decoded_request['tags']
