DNS Servers: Web UI part
Adds new page with DNS Servers and details page about each server.
It is counterpart of dnsserver-{find,show,mod} CLI commands.
Part of: https://fedorahosted.org/freeipa/ticket/5905
Reviewed-By: Petr Spacek <pspacek@redhat.com>
Reviewed-By: Petr Vobornik <pvoborni@redhat.com>