Add binding for virDomainInterfaceAddresses.

A straight-forward 1:1 mapping to the C API. Returns array in the
following format:

array (
  0 =>
  array (
    'name' => 'vnet0',
    'hwaddr' => '52:54:00:3a:cd:94',
    'naddrs' => 1,
    'addrs' =>
    array (
      'addr' => '192.168.254.224',
      'prefix' => 24,
      'type' => 0,
    ),
  ),
)

Signed-off-by: Dawid Zamirski <dzamirski@datto.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>