Allow option to bypass certificate verificaiton

On-Premise clients using self-signed certificates will sometimes hit the following error:

Error in curl::curl_fetch_memory(url, handle = handle) :
Peer certificate cannot be authenticated with given CA certificates

This can be resolved by bypassing certificate checking by adding the following line before making the request:

httr::set_config(config(ssl_verifypeer = 0L))

It would be nice if this option were configurable within the Plotly .config file.

首先定位 Plotly .config 选项的解析方式，以及使用 httr 发出请求的位置。检查如何通过现有配置路径传递 ssl_verifypeer。完成标准是：on-premise 客户端可以通过 .config 选择退出证书验证，同时默认行为保持不变。