We're trying to stay up to date on virtualenv releases so we don't fall
too far behind and so we can leverage new features, such as wheels.
This virtualenv release features upgrades to pip (1.4.1 to 1.5.4) and
setuptools (0.9.8 to 2.2). These may fix bugs people are encountering
in the wild.
Tarball obtained from
https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.11.4.tar.gz#md5=9accc2d3f0ec1da479ce2c3d1fdff06e.
the egg-info directory was removed (consistent with previous virtualenv
upgrades).
