Buffer::append_dns_label: new function to append string using DNS format.
DNSQuery::set_header: fix, increase buffer index.

* create_answer: change parameters based on RR format.
* change _ttl back to unsigned integer.
DNS_rr: add method INIT and create_packet.

* _ttl: change to unsigned int.
libvos: include stdint.h.
DNS_rr::create_packet: fix data length.
DNSQuery::create_answer: remove debug.