Added fixes so BuyPass Go ACME server can be used

[mysteq]

Had to add a few tweaks to be able to use the ACME server for BuyPass GO, as it seems to not quite conform to the ACME v1 specs implemented currently in acme.sh.

Resources:
https://api.buypass.com/acme/directory
https://www.buypass.com/ssl/resources/go-ssl-technical-specification

The tweaks should not affect existing functionality, and I've done some basic testing on CentOS.

[Neilpang]

If certbot can work out of the box aginst buypass, we should also be able to.
I don't think we need so much buypass specific tricks.

please fix it in the code directly, I think it's in the ACME v1 specific blocks.

Thaanks

[Neilpang]

I think we should be able to remove any "buypass" or "BUYPASS" string from the code.
please go ahead.

[mysteq]

Changed the code to fix it directly in v1 code then.

Tested this with CloudFlare DNS authorization on a CentOS 7 server, with:
Let's Encrypt Staging v1
Let's Encrypt Staging v2
BuyPass

[Neilpang]

remove it

[m-ueberall]

Apologies if this has been mentioned elsewhere, but I did not find it: Where are certificates being kept if you use the exact same parameters/(sub)domains but reference different server URIs/CAs?
I'm not sure the resulting files can coexist in ~/.acme.sh/sub.domain.tld[_ecc]--will users get to see a warning when existing files from a different CA would be overwritten or should this at least be mentioned somewhere else?

[Neilpang]

@m-ueberall

will users get to see a warning

Yes, if there is an existing cert, no matter from the same CA or a different CA, the user always gets a warning.

The user MUST use --force parameter to overwritten the existing cert.