Fix dnsrecord_add interactive mode

dnsrecord_add interactive mode did not work correctly when more
than one DNS record part was entered as command line option. It
asked for remaining options more than once. This patch fixes
this situation and also adds tests to cover this use case
properly.

https://fedorahosted.org/freeipa/ticket/2641

ipalib/plugins/dns.py

@@ -2046,7 +2046,7 @@ class dnsrecord(LDAPObject):
                 continue
 
             if rrparam.name not in processed:
-                processed.append(rrparam)
+                processed.append(rrparam.name)
                 yield rrparam
 
 api.register(dnsrecord)