Create secondary zones automatically
From discussion on #4179
Add possibility to add secondary zones automatically through the DNS wizard.
You should be able to add those zones to the wizard template, along with their settings (NS IP, xfer).
There are several ways to go, we have to keep in mind that in the future we probably want to use traditional mirroring again by saving the keys to the database and replicating that to the ISPConfig mirrors. Read discussion(s) on #4179 about possible ways to implement this.