Bug in resolver.py for Python3 on Windows

[spe...@custodela.com]

So I just installed and tested the latest version of DNSPython for Python3. Seems to not fully support python 3 since it's referencing the _winreg instead of winreg. 

Writing C:\Python33\Lib\site-packages\dnspython3-1.10.0-py3.3.egg-info

d:\inet\dns\dnspython3-1.10.0>cd ..

d:\inet\dns>py test.py

Traceback (most recent call last):

  File "test.py", line 8, in <module>

    import dns.resolver

  File "C:\Python33\lib\site-packages\dns\resolver.py", line 38, in <module>

    import _winreg

ImportError: No module named '_winreg'

Replace all _winreg with winreg and the module seems to load.