GitLab

- Re-evaluate feature set and REST API.
- switch duration units to days, which are more meaningful than sticking to
  ISO units in this context.
- Implement the "cau" half of "caucase".
  As a consequence flask password authentication mechanism is not needed
  anymore. As HTML UI is not required internally to caucase, and as
  sqlalchemy is not used to its full extend, get rid of these
  dependencies altogether.
- Implement REST HTTP/HTTPS stand-alone server as a layer above WSGI
  application, and integrate HTTPS certificate issuance and renewal
  mechanism to simplify deployment: no middleware needed, so from
  gunicorn dependency.
- Use standard python modules for http client needs.
- Re-evaluate data retention options:
  - unsigned CSRs are kept forever
  - CRTs are stored in CSR table, and a 24 hour expiration is set
  - CA CRTs: (unchanged, expire when past validity period)
  - CRLs: (unchanged, expire when past validity period)
- Redispatch housekeeping tasks:
  - CA renewal happ...