python3: travis testing for python 3

Turn on travis testing for Python 3.

partial: https://github.com/vmware/pyvmomi/issues/55
python3: urlib2 to requests

migrate from urllib2 to requests in the connect.py module. starting to
fix issue #13

partial: https://github.com/vmware/pyvmomi/issues/55

see also: https://github.com/vmware/pyvmomi/pull/66
python3: remove unused imports

We can now safely remove these imports.

partial: https://github.com/vmware/pyvmomi/issues/55
python3: absolute import

Use absolute import from the __future__ module to prepare
the library for use in python 3

partial: https://github.com/vmware/pyvmomi/issues/55
python3: Iso8601 print_function

Moves Iso8601 to using the print_function.
NOTE(should not use print at all here)

partial: https://github.com/vmware/pyvmomi/issues/55
python3: 2to3 tool

Fixes for Python 3 with 2to3

partial https://github.com/vmware/pyvmomi/issues/55
python3: more 2 to 3 tool fixes

Changes exception statements to match python 3 style

partial: https://github.com/vmware/pyvmomi/issues/55
python3: unicode - minimalist change set

A minimal change set to deal with unicode modules and methods between
python2 and python3. A deeper reworking of the unicode components
is very likely called for, however, this change should get the library
working on python3.

partial: https://github.com/vmware/pyvmomi/issues/55
python3: string formatting

remove all old style string formatting from Soapadapter.py and move to
.format() syntax for python 3 compatibility

partial https://github.com/vmware/pyvmomi/issues/55
python3: travis environment tweaks

Travis CI configuration tweaks for python3 support

partial: https://github.com/vmware/pyvmomi/issues/55
python3: unittest define main

Code change to unit tests for python3.

partial: https://github.com/vmware/pyvmomi/issues/55
python3: version neutral API

Using the six library we make version neutral API calls to
dictionary methods and to unicode methods.

partial: https://github.com/vmware/pyvmomi/issues/55
python3: replace thread module with threading

partial: https://github.com/vmware/pyvmomi/issues/55
python3: change call to urlparse

partial: https://github.com/vmware/pyvmomi/issues/55
python3: fix some syntax errors

partial: https://github.com/vmware/pyvmomi/issues/55
Merge pull request #88 from hartsock/python3

Support for Python 3
Merge pull request #89 from vmware/python3

Support for Python 3
python3: fix serializer

Python 3 series improper serialization
... introduces a 'b' character in front of string.

fixes https://github.com/vmware/pyvmomi/issues/90
Merge pull request #91 from hartsock/python3

python3: fix serializer
python3: fix reraise

Related to six bug https://bitbucket.org/gutworth/six/issue/86/sixreraise-exception_object-none-traceback

closes: https://github.com/vmware/pyvmomi/issues/92