Restore compatibility with Python 2.4 (Plone 3).
Update setuptools.

Now the buildout and the test run with my local python2.4 after having updated that to the most recent non-patched setuptools.
Why bin/buildout now complains when I try to pin it to 1.1.5 (which I have installed globally)
instead of 1.1.4: I have no idea.
Tests: use the standard pypi url.