Make client server option multi-valued, allow disabling DNS discovery
Let the --server option be specified multiple times on the command line.
The first one passed in is the one we enroll against.
Do additional verification before setting dnsok so we can be sure that
the record(s) were actually discovered in DNS.
If servers are provided on the CLI and --fixed-primary is set then
_srv_ is not added to ipa_server in sssd.conf.
https://fedorahosted.org/freeipa/ticket/2841