Matplotlib depends on numpy, so we want to ensure the correct version
of numpy is already installed when we attempt to install matplotlib.

With 2.0.1, and setuptools 34.0.2, errors happen like:

File "/edx/app/edxapp/venvs/edxapp-sandbox/local/lib/python2.7/site-packages/packaging/requirements.py", line 59, in <module>
    MARKER_EXPR = originalTextFor(MARKER_EXPR())("marker")
TypeError: __call__() takes exactly 2 arguments (1 given)

(cherry picked from commit 73519b35)

So that we can use setuptools instead of distribute

Used by MITx/6.341x