Return correct record name in DNS plugin
When dnsrecord-add or dnsrecord-mod commands are used on a root
zone record (it has a special name "@"), a zone name is returned
instead of a special name "@". This confuses DNS part of Web UI
which is then not able to manipulate records in the root zone
when these commands are used.
This patch fixes these 2 commands to return correct value when
a root zone is modified.
https://fedorahosted.org/freeipa/ticket/2627
https://fedorahosted.org/freeipa/ticket/2628