- Add zip_safe flag

reStructuredText is quite picky

Added instructions and an example for changing the default user-agent,
as in: https://meta.wikimedia.org/wiki/User-Agent_policy .

Also replaced relative links in the README, since PyPI doesn't support
them, see http://stackoverflow.com/a/16594755/489916

since the method does not edit the page, but returns the text of the
page. The old method name still works, but issues a DeprecationWarning.
Note that DeprecationWarnings are silent by default, so we might
consider to elevate it in some future version.

If we do change it later, then we can update the readme accordingly.

- Increase version requirement from Python 2.4 to Python 2.6, and from MediaWiki 1.11 to 1.16
- Add three entries to release notes

- For some reason, 'pytest-cache' isn't found by setup.py if not
  specified explicitly in 'tests_require'
- Add tox.ini so tests can be run using tox if desired
- Update test to not be dependent on serialization

- 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.

- Adding note that 0.6.5 might not work with the latest MediaWiki versions
- Fix link to wiki

simplejson is now a requirement installed by easy_install, pip
or other toos. ReadMe was converted from MarkDown to reStructuredText
to make it usable at PyPI while still being supported by GitHub.