Move away from rackspace #5

The hosting on rackspace of http://wheels.scipy.org is no more. Other MacPython projects have moved to using https://anaconda.org/scipy-wheels-nightly/ for weekly uploads and https://anaconda.org/multibuild-wheels-staging for staging wheels to PyPI. Another option is to use github for staging like cython for travis and for appveyor. Here is the numpy code (on travis) to upload to anaconda https://github.com/MacPython/numpy-wheels/blob/master/.travis.yml#L99

If you want to use anaconda, you have access to tokens via the "Organization Secrets" https://github.com/MacPython/numexpr-wheels/settings/secrets if you can move to github actions (they provide x86 machines for windows, linux and mac). Otherwise we will need to negotiate getting you tokens.

xref @matthew-brett. We should copy this to all projects in the org.