Use six to fix imports on Python 3

Use six to fix imports on Python 3

Replace Python 2 imports with six.moves import to make code compatible
with Python 2 and Python 3.

Replaced imports:

* BaseHTTPServer
* __builtin__
* cookielib
* httplib

This patch was generated by the six_moves operation of the sixer tool
version 0.4:
https://pypi.python.org/pypi/sixer

Manual changes:

* Disable pylint warnings on the HTTPSConnection classes because pylint
  doesn't support importing from six.moves yet, see:
  https://bitbucket.org/logilab/pylint/issue/550/

Blueprint cinder-python3
Change-Id: Ide6d4e3480f2c0a7eb4500aa88affe152ecc0401