cipango-dns
 - Migrate module from cipango 2
 - DNS service now read etc host file
 - Record implements equals
 - Duplicate entries are no more set in cache

Signed-off-by: Nicolas <nicolas@cipango.org>
Add DnsResolver

Signed-off-by: Nicolas <nicolas@cipango.org>
Add support to RFC 3263 with retry and black list.
cipango-dns is now manageable

Signed-off-by: Nicolas <nicolas@cipango.org>