'Get a new token from the internal metadata service.
:return:  Dictionary containing token information
:rtype:   ``dict``'

def get_new_token(self):

    path = '/instance/service-accounts/default/token'
    (http_code, http_reason, token_info) = _get_gce_metadata(path)
    if (http_code == httplib.NOT_FOUND):
        raise ValueError('Service    Accounts    are    not    enabled    for    this    GCE    instance.')
    if (http_code != httplib.OK):
        raise ValueError(("Internal    GCE    Authorization    failed:    '%s'" % str(http_reason)))
    token_info = json.loads(token_info)
    if ('expires_in' in token_info):
        expire_time = (_utcnow() + datetime.timedelta(seconds=token_info['expires_in']))
        token_info['expire_time'] = _utc_timestamp(expire_time)
    return token_info
