Manage zone records

[BDelacour]

See #196

@ekohl Is it OK for you to manage zone without validation or would you prefer a more specific type (which would lead to a configuration more difficult to maintain) ?

Example :

• I created something like this (in Hiera)

dns::zones:
  example.com:
    replace_file: true
    serial: 2
    records:
      - host1 IN A 192.168.0.1
      - host2 IN A 192.168.0.2

• Or you want something like this (don't mind the naming, just for the format)

dns::zones:
  example.com:
    replace_file: true
    serial: 2
    records:
      - name: host1
         xx: IN
         type: A
         dst: 192.168.0.1
...

[ekohl]

Since you explicitly pinged me, I gave it a quick look but I'm on leave so officially not working. @evgeni / @ehelms would you mind taking care of this? I just approved CI so the tests can run and some minor inline comments on small details, but the general idea looks good to me.