Feature Request: Manage Scrapyd servers via the web instead of configuration file.

[imaxwen]

Hi there~

First, thanks for your Great job, this project made our scrapyd management super easy.

we have lots of scrapyd servers deployed and usually we add new servers for new projects or remove servers when they were unnecessary. Every time the servers changed, we have to update the configuration file, and then restart scrapydweb application.

Hopefully if we can manage the servers dynamically via the web, that will be great 👍