* Added possibility to use an existing config file for recursor or authorative mysql-powerdns-server, in case the configuration file is handed in from a volume or bind mount (in which it should be mounted as read only!).
* ammended changes to PostgreSQL init to provide the same features as the MySQL one.
* do not forget to init superslaves if needed.
* typos and really do install config file by environment.
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Co-authored-by: Kai Schlachter <kai.schlachter@bahag.com>