iteritems => items for py3 compat

[msabramo]

With this and #7, I can get it to work on Python 3.4.

[marca@marca-mac2 teamcity-python-rest-client]$ git branch
  add_sample
  gitignore
  iteritems_to_items
  master
* msabramo_master
  py3
  remove_print
  setup_py
  tox
  use_requests

[marca@marca-mac2 teamcity-python-rest-client]$ git log -n 1
commit bf0c2018bb7100fe9201e9a2af6d88b9ff1df031
Author: Marc Abramowitz <marc@marc-abramowitz.com>
Date:   Tue Feb 24 12:39:55 2015 -0800

    iteritems => items for py3 compat

[marca@marca-mac2 teamcity-python-rest-client]$ tox
...
  py26: commands succeeded
  py27: commands succeeded
  pypy: commands succeeded
  py33: commands succeeded
  py34: commands succeeded
  congratulations :)