Add ipaddress.py to fix issue #1
Add ipaddress.py to fix issue #1

Python standard module "ipaddress" is provided by Python 3.3 or later.
This commit implements ipaddress.py for Pyhton3.2.

This ipaddress.py implements some functions which have
the same API as Python startd module "ipaddress".

If Python 3.3 or later are available, Python standard module "ipaddress"
should be used instead of this ipaddress.py.

kusm/dnschecker,kusm/dnschecker