Python3 support for xmlrpclib

Python3 actually does include xmlrpc(lib). It's just called
xmlrpc.client. The class and function signatures are the
same as the old Python2.x xmlrpclib module.

Adds a note that six.moves should be used once six 1.4.2 is
released. See http://bit.ly/1bqrVzu.

References:

Python 2 xmprpllib doc: http://docs.python.org/2/library/xmlrpclib.html
Python 3 xmlrpc.client doc: http://docs.python.org/3/library/xmlrpc.client.html

Change-Id: I478b56f22d02350a21093a887d9f6fcb84958724
Merge "Python3 support for xmlrpclib"