Python 3.4 is EOL and support for it has been removed by
the requests package that we depend on.

Python 3.3 is EOL, and is failing on Travis.

Remove python2.6 from
- Travis
- Tox
- PyPi tags
- documentation and readme

Also, Simplify an import clause.

This fixes #133

Should at least be compatible with Python 3.4 now.
Can't get Python 3.3 to work locally, but let's see with Travis.

- A single command `python setup.py test` will now install test
  dependencies, make an in-place build and run the tests.
- The setup script now requires Setuptools. A message will be printed
  if it is not found.

- Note the following exception replacements:
  mwclient.errors.HTTPError -> requests.exceptions.ConnectionError
  mwclient.errors.HTTPStatusError -> requests.exceptions.HTTPError
  mwclient.errors.HTTPRedirectError -> requests.exceptions.TooManyRedirects

- Removed the `compability.old_upload` method, which was used for
  MediaWiki < 1.16.

- Requests automatically decompresses gzip-encoded responses, and
  does its best to decode response content to unicode when possible.

- [#53] Using the Responses library to mock http requests in tests

- Keep automated tests to be run with py.test in './tests/'
  and examples in './examples/'
- Rename test to adhere to 'Conventions for Python test discovery'
  (http://pytest.org/latest/goodpractises.html#test-discovery)

Adding pytest.ini to ignore E501 long lines for convenience
and W602 since we want to retain backwards compability