.travis.yml: Don't install distribute

http://python-distribute.org doesn't seem to be up anymore, which is
not surprising so long after the Distribute/Setuptools merge of
2013-06-01 [1].  This reverts 3b41da8d6 (Fix travis CI builds,
2014-02-04).

Instead, we run 'make setup' with sudo to avoid:

  $ make setup
  ...
  error: invalid command 'egg_info'

[1]: https://pythonhosted.org/setuptools/merge-faq.html#what-is-the-timeframe-of-release
Merge pull request #365 from wking/mongo-vow-get-nothing-server

vows.mongo_storage_vows: Set a server in GetNothingAfterExpiration
Merge pull request #364 from wking/remove-distribute

.travis.yml: Don't install distribute
vows.url_vows: Remove old_format reference

The argument was removed by f015a672 (Either we have unsafe or a hash,
we can't have both, 2012-07-09), which has left me with:

  $ make test
  ...
      Url vows
        Regex
          With old format

           Error in topic:
            regex() got an unexpected keyword argument 'old_format'

            Traceback (most recent call last):
              File "/.../pyvows/runner/gevent.py", line 104, in _run_setup_and_topic
                topic = topic_func(*topic_list)
              File "/.../vows/url_vows.py", line 134, in topic
                return Url.regex(old_format=True)
            TypeError: regex() got an unexpected keyword argument 'old_format'
  ...
CONTRIBUTING.md: Rename from CONTRIBUTING

Currently, GitHub renders the page as raw text.

[1]: https://github.com/thumbor/thumbor/blob/master/CONTRIBUTING
CONTRIBUTING.md: Bump minimum Pillow version to match setup.py

And test_requirements.txt, which has the same thing that setup.py
does.
test_requirements.txt: Float Pillow up to (but not including) 3.0

The current Pillow version is 2.6.0 (released 2014-10-01 [1]), and
2.4.0 is stable on Gentoo.  Instead of being very conservative here,
assume Pillow uses semantic versioning [2] and will bump to 3.x if
they break backwards compatibility.  Folks who are skeptical of their
local Pillow can use the test suite to verify it, and we can blacklist
any versions that we know are bad.

It's a bit stickier if Pillow is broken for some version on only a
subset of systems, such as Pillow < 2.3.0 with FreeType >= 2.5.1
[3,4].  In that case, I'd probably just up the minimum requirement to
2.3.0, but I'm also ok leaving it up to the local packagers to sort
these things out (and shame on the FreeType folks for changing their
header installation in a patch release!).

[1]: https://pypi.python.org/pypi/Pillow/2.6.0
[2]: http://semver.org/
[3]: https://github.com/thumbor/thumbor/issues/248
[4]: https://github.com/python-pillow/Pillow/issues/425
Bump minimum Pillow version to 2.3.0

To avoid incompatibilities with FreeType >= 2.5.1 [1,2].

[1]: https://github.com/thumbor/thumbor/issues/248
[2]: https://github.com/python-pillow/Pillow/issues/425
Merge remote-tracking branch 'wking/cleanup-old-format' into wtk
Merge remote-tracking branch 'wking/contributing-markdown' into wtk
Merge remote-tracking branch 'wking/pillow-version-range' into wtk