Dnsrobocert

Modified
* Upgrade Lexicon to 3.4.3 (add Njalla provider)
* Upgrade Certbot to 1.8.0

Modified
* Upgrade Lexicon to 3.3.28
* Upgrade Certbot to 1.7.0
* Upgrade Docker base image to Alpine 3.12

Modified
* Modify dependencies versions pinning to fix the docker images builds

Added
* `autocmd.command` now accepts list of string. If a list of string is provided, the command will
be executed outside of a shell. If a string is provided, it will be executed inside a shell.
The list of string form should be used if you do not need the features of a shell since it allows
a better control of the arguments passed to the command and avoid potential injections attacks.

Modified
* Upgrade Lexicon to 3.3.27 (support for Dynu.com provider)
* Upgrade Docker base image to Alpine 3.12

Added
* DNS challenges are now all run before any wait or check happens. This is useful for certificates that
contains lot of domains, because DNSroboCert will wait only once the provided `sleep_time`, instead
of waiting after each challenge. This optimizations is also valid for `max_checks`.

Modified
* Improve log output from the auth and cleanup hooks.
* Improve documentation.

Modified
* Upgrade Lexicon to 3.3.26 (fix errors with Godaddy provider)