Waitress is used as the WSGI server.

Instead of expensive and long checking of the configuration during promise run
read last stored state.

This decouples configuration validation calculation from promise check. The
validation information is updated often (on each configuration change, on each
reload, etc) and every 2 hours.

Validation happens on each configuration change, but for sure it is checked
each 2 hours.

State of configuration is calculated in separate script.

Order of files does not matter for the assertion.

Tests need to open xz files for checking.

It's interesting what appears in cron entries, as they are important for proper
partition usage.

Always work from the slave_dir path for extensibility and allow no ignore
paths if caller does not need to ignore anything.

Ignore path's shall be relative to checked directory.

Move files from var/log/trafficserver/*old to
srv/backup/logrotate/trafficserver, xz them and clean files older than a
year.

As some tools are not configurable with logrotate provide a script to
"rotate" files generated by those tools.
This script more or less follows logrotate behaviour:

 * moves rotated files to logrotate directory
 * compresses them with xz
 * have to be configured to keep only files for some days

Roll logs each 24h, as it would be expected.

  Upper limits makes harder deploy larger systems

Stderr to null redirection happened in the wrong place.

/reviewed-on nexedi/slapos!561

Promises will fail with stderr filled, and it can be such if sha256sum emits
error messages, so just discard them.

Some arguments needs Caddy process restart, so implement it with
hash-files and also inform the master partition requester about parameters
which will result with process restart.

Kedifa partition was missing monitoring at all, so add it and monitor kedifa
and exposer ip and port.

Partition running caddy was missing monitoring for exposer, so add it.

Use unreal address to avoid any tries for network connectivity.

Kedifa requires some time to process new slave, and during that time the key
download URL is not available, but as it is required for proper mapping file,
use some url to mimic it.

Recent setuptools found a way to install by downloading wheels from PyPI.
But we want to control the versions of all components.

Buildout's kedifa updater just prepares, and so real one has to be run.

During buildout run no network communication is required in order to prepare
fallback certificates, so call kedifa-updater with --prepare-only

It is needed by users to check certificate of KeDiFa while uploading
certificates.

Each time new slave appears the kedifa-updater has to be run immediately, in
order for certificates to be properly setup.

Otherwise caddy can be left in non-runnable state until next kedifa-updater
would run again.