core: fix for working with python 3.3

The unfixed parse_querystring() raises the following exception
in Python 3.3:

  TypeError: Type str doesn't support the buffer API

Also removed iteritems() as it is deprecated and no longer
supported in Python 3.x
Merge pull request #115 from melor/py33

core: fix for working with python 3.3
New release: 0.7.1
tips
removing requirements.pip, requirements now reside solely in requirements.txt
fix(travis): reqs.pip -> reqs.txt
feat: tox support

tox makes it easy to verify whether tests pass across a variety of
different python versions.

This patch adds that support.
Merge pull request #128 from cabrera/travis

fix(travis): reqs.pip -> reqs.txt
Merge pull request #129 from cabrera/tox_support

feat: tox support
begun to work in python 3.3 support
more fixes
Merge pull request #133 from CyrilRoelandteNovance/py3_rebased

Py3 rebased