Add CLI support to convert a whole folder at once

[andylobel]

From json to bind and vice-versa

E.g. zonefile -g dns-zones/json --out dns-zones/bind --extension ".txt"

[elgs]

Try if this bash script works:

#!/bin/bash

for filename in dns-zones/json/*.json; do
    zonefile "$filename" > "dns-zones/bind/$(basename "$filename" .json).txt"
done