python-netaddr: new package

Signed-off-by: Mauro Condarelli <mc5686@mclink.it>
Reviewed-by: Yegor Yefremov <yegorslists@googlemail.com>
[Thomas:
  - remove excessive empty new line at the end of Config.in
  - specify BSD-3c as the license, since it's the variant being used,
    and it's more specific than just BSD.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>