did not get response header cookie Secure?

 - did not get Secure?

``` 
"Set-Cookie: X_SADG_RouterID=test"
"Set-Cookie: tag=sign-8080; path=/; Secure"
```

 - demo

```
    local fields, err = cookie:get_all()
    if not fields then
        ngx.log(ngx.ERR, err)
        return
    end

    for k, v in pairs(fields) do
        ngx.log(ngx.ERR, "=============" .. k .. " => ", v)
    end
```

