Add ability to keep the HTTP-01 challenge file

[josegonzalez]

Welcome

• Yes, I've searched similar issues on GitHub and didn't find any.

How do you use lego?

Docker image

Detailed Description

I use lego in the dokku project via dokku-letsencrypt. Very often, users have issues with letsencrypt - permissions, some firewall bug, etc. - and it's hard to debug what the issue is due to the challenge file being cleaned up.

It would be great to have an option like --http-disable-cleanup. This would disable the removal of the challenge file, allowing the Dokku project to enable this as a sort of "debug mode" so that I can help debug installations where I don't have direct SSH access for whatever reason.