Obtain SSL certificates from the letsencrypt.org ACME server. Suitable
for automating the process on remote servers. Features:

- Bash - It runs on virtually all unix machines
- Get certificates for remote servers (script doesn't need to run on the
  server itself)
- Runs as a daily cron - so certificates will be automatically renewed
- Checks certificates are correctly loaded
- Extensively configurable
- Supports http and dns challenges
- Simple and easy to use
- Detailed debug info
- Reload services
- ACME v1 and V2
