core: fix for working with python 3.3

[melor]

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

---

The same (or just very similar?) problem is mentioned in https://github.com/gabrielfalcao/HTTPretty/pull/27/files

The original exception:

        try:
            self.sock.sendall(data)
        except TypeError:
            if isinstance(data, collections.Iterable):
                for d in data:
>                   self.sock.sendall(d)

/usr/lib64/python3.3/http/client.py:875:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <httpretty.core.fakesock.socket object at 0x7fe1197e6a90>, data = 71, args = (), kw = {}

    def sendall(self, data, *args, **kw):
        self._sent_data.append(data)

        try:
>           requestline, _ = data.split(b'\r\n', 1)
E           AttributeError: 'int' object has no attribute 'split'

../../env/test/lib/python3.3/site-packages/httpretty-0.7.0-py3.3.egg/httpretty/core.py:346: AttributeError

[z4r]

Hi @melor, i've the same problem: https://travis-ci.org/z4r/python-coveralls/jobs/13962388

[zulcss]

This patch fixes it for me.