Persistency is achieved by taking apart the setup-kolab procedure,
and storing the data in mounted volumes by symlinking the various
directories in bind mounts.
The approach is inspired by the upstream containerization efforts.

Second the container networking is isolated except for meet (for which
we continue to use host-networking due to the large port ranges in use)

This patch also:

• Resolves the kolab containers dns request via powerdns: By pointing dns to powerdns for the kolab container (via static ip), we can resolve woat queries. For powerdns to start we have to make sure the tables are available from the start,which means we have to drop them again during the migration.
• Merges all config adjusting scripts in the kolab container
• Fixes the certificate paths in the proxy
• Provides backup and restore scripts for the volumes containing the data
• Fixes various docker-compose startup order issues
• Splits docker-compose services, which we only use for building images, into a separate docker-compose file. This way docker-compose up/stop/... work as expected.
• Cleans up the environment variables some, and sets the defaults for a local docker deployment.