Rewrite debops.dnsmsq role

'debops.dnsmasq' role has been completely redesigned:

- you can now configure multiple network interfaces at the same time,
  dnsmasq role will read IPv4 and IPv6 addresses from specified interfaces
  and automatically configure DHCP, DNS and TFTP services for them;

- dnsmasq role now supports IPv6 networks and automatically configures
  DNS entries for IPv6 addresses when using dual-stack network with IPv4
  addresses;

- you can allow access to DNS server from upstream networks and publish
  public DNS information by delegating your subdomain in your main DNS
  zone, this should help with access to internal IPv6 hosts;

- you can enable or disable DHCPv4, DHCPv6, Router Advertisements and
  TFTP services separately as needed;

- CNAME support has improved, records are automatically created for the
  'host' part, 'host.router' and full 'FQDN';