[pve-devel] RFC V2 for ACME DNS Challenge

[Wolfgang Link]

These patches are just the acme.sh thin wrapper part for the reuse of the dnsapi.
In this version I use curl instead of wget.
Curl is already part of PMG, and PVE has libcurl packages dependency.
This script has additionl an additional on
    - coreutils (an we ignore)
    - sed (must be installed)
    - curl (just the frontend)
    - idn (just dns_cyon is using it so that I wouldn't make a dependency for it.
      If a user likes to use cyon, he will get an error to install idn.)